Show Working

GCSE PhysicsAQA, Edexcel and OCR

Physics required practicals: GCSE questions with answers

40 questions on the physics required practicals. Pick your answer, then tap to see if you were right and why. Every answer comes from the Show Working science bank, checked against the GCSE content every board in England teaches.

Quiz yourself: 40 questions 8 6-mark questions

01 / Quiz yourselfTry it, then tap to check

Physics required practicals questions to try

Choose your answer before you open it. Then read why, so it sticks.

01 / Physics required practicalsBoth tiers

What does the specific heat capacity practical find out about a material?

  1. AThe energy needed to warm 1 kg of it by 1 °C
  2. BThe energy needed to melt 1 kg of it
  3. CHow quickly it cools down in a cold room
  4. DThe temperature at which it starts to melt
Show the answer

Answer: A The energy needed to warm 1 kg of it by 1 °C

You supply a measured amount of energy, measure the mass and the temperature rise, and work out the energy needed per kilogram per degree. That value is the specific heat capacity, in J/kg °C.

Checked against AQA GCSE Physics 8463 specification, 8.2.1 Required practical activity 1

02 / Physics required practicalsBoth tiers

Which meter reads the energy supplied by the heater directly?

  1. AAn ammeter
  2. BA newtonmeter
  3. CA joulemeter
  4. DA voltmeter
Show the answer

Answer: C A joulemeter

A joulemeter shows the energy transferred in joules. Without one, measure the current with an ammeter, the potential difference with a voltmeter and the time with a stopwatch: energy = current × potential difference × time.

Checked against OCR Gateway Physics A J249 specification, P1.2 specific heat capacity (PAG P5)

03 / Physics required practicalsBoth tiers

You heat a metal block and record its temperature every minute. What is the dependent variable?

  1. AThe temperature of the block
  2. BThe mass of the metal block
  3. CThe setting of the power supply
  4. DThe time since the heater was switched on
Show the answer

Answer: A The temperature of the block

The temperature of the block is what you measure as the result. The energy supplied (or the time) is what changes as you go, and the power supply setting stays the same so energy goes in at a steady rate.

Checked against AQA GCSE Physics 8463 specification, 8.2.1 Required practical activity 1

04 / Physics required practicalsBoth tiers

Why is the block or beaker wrapped in insulation?

  1. ATo reduce energy lost to the surroundings
  2. BTo stop the heater switching itself off
  3. CTo stop it conducting electricity
  4. DTo make the thermometer reading steadier
Show the answer

Answer: A To reduce energy lost to the surroundings

Some of the energy supplied heats the air instead of the material, so the temperature rise is smaller than it should be. Dividing the energy by too small a rise gives a specific heat capacity that is too high. Insulation reduces this.

Checked against OpenStax Physics, 11.2 Heat, specific heat and heat transfer

05 / Physics required practicalsBoth tiers

Why are a few drops of water or oil put in the hole for the thermometer?

  1. AIt cools the thermometer down first
  2. BIt improves thermal contact with the block
  3. CIt makes the scale easier to read
  4. DIt insulates the thermometer from the block
Show the answer

Answer: B It improves thermal contact with the block

Air is a poor conductor, so an air gap round the thermometer bulb would make it lag behind the real temperature of the block. A little water or oil fills the gap so energy reaches the thermometer quickly.

Checked against AQA GCSE Physics 8463 specification, 8.2.1 Required practical activity 1

06 / Physics required practicalsBoth tiers

Put these steps for finding the specific heat capacity of a metal block in order.

  1. ARecord the starting temperature
  2. BMeasure the mass of the block on a balance
  3. CSwitch on the heater
  4. DPut the heater and thermometer into the block
  5. ERecord the energy supplied and the temperature rise
Show the answer

The right order:

  1. Measure the mass of the block on a balance
  2. Put the heater and thermometer into the block
  3. Record the starting temperature
  4. Switch on the heater
  5. Record the energy supplied and the temperature rise

Find the mass first, then set up the heater and thermometer and take the starting temperature before any energy goes in. Then heat, and record the energy supplied and the temperature rise to work out the specific heat capacity.

Checked against AQA GCSE Physics 8463 specification, 8.2.1 Required practical activity 1

07 / Physics required practicalsBoth tiers

What is the main hazard in the specific heat capacity practical?

  1. AMains voltage is connected to the block
  2. BThe heater gets hot enough to burn skin
  3. CThe metal block gives off toxic fumes
  4. DThe joulemeter can explode if left on
Show the answer

Answer: B The heater gets hot enough to burn skin

The heater runs from a low-voltage supply, so the real hazard is heat. It stays hot for a while after switching off, so leave it in the block or water to cool and do not touch it.

Checked against OCR Twenty First Century Physics B J259 specification, P6.1 How does energy transform matter?

08 / Physics required practicalsBoth tiers

Two materials of equal mass are heated. On a graph of temperature against energy supplied, a steeper line shows:

  1. AA lower specific heat capacity
  2. BMore energy lost to the air
  3. CA higher specific heat capacity
  4. DA larger mass of material
Show the answer

Answer: A A lower specific heat capacity

A steeper line means each joule raises the temperature more. A material that needs less energy per kilogram per degree has a lower specific heat capacity, so for equal masses it gives the steeper line.

Checked against OpenStax Physics, 11.2 Heat, specific heat and heat transfer

09 / Physics required practicalsBoth tiers

Two resistors are joined in series. How does their total resistance compare with either one alone?

  1. AIt is larger
  2. BIt is smaller
  3. CIt is zero
  4. DIt is the same
Show the answer

Answer: A It is larger

In series the charge must pass through both resistors, so their resistances add. In parallel there are two paths for the current, so the total resistance is less than the smallest single resistor.

Checked against OpenStax Physics, 19.3 Parallel circuits

10 / Physics required practicalsBoth tiers

In an I-V practical, what is used to get a range of different currents through the component?

  1. AA fixed resistor
  2. BAn extra ammeter in series
  3. CA switch
  4. DA variable resistor
Show the answer

Answer: D A variable resistor

A variable resistor, or a variable power supply, changes the p.d. across the component so you can take a range of readings. Reversing the connections makes the current flow the other way, giving negative values.

Checked against AQA GCSE Physics 8463 specification, 8.2.4 Required practical activity 4

11 / Physics required practicalsBoth tiers

What I-V graph does a fixed resistor at constant temperature give?

  1. AA curve that gets flatter as p.d. rises
  2. BA horizontal straight line
  3. CA line on one side only
  4. DA straight line through the origin
Show the answer

Answer: D A straight line through the origin

At constant temperature the current through a fixed resistor is directly proportional to the p.d. across it, because its resistance does not change. That gives a straight line through the origin.

Checked against OpenStax Physics, 19.1 Ohm’s law

12 / Physics required practicalsBoth tiers

Why does the I-V graph of a filament lamp curve?

  1. AIts resistance decreases as it gets hotter
  2. BThe p.d. across it stays the same
  3. CIts resistance increases as it gets hotter
  4. DThe current is used up in the filament
Show the answer

Answer: C Its resistance increases as it gets hotter

A bigger current heats the filament. The ions in the hot metal vibrate more, so the moving electrons collide with them more often and the resistance rises. The graph gets flatter at higher p.d.

Checked against AQA GCSE Physics 8463 specification, 8.2.4 Required practical activity 4

13 / Physics required practicalsBoth tiers

How do you find the volume of an irregular object such as a small stone?

  1. AMeasure the volume of water it displaces
  2. BMeasure its length with a ruler
  3. CWeigh it and halve the mass
  4. DMeasure how much water it soaks up
Show the answer

Answer: A Measure the volume of water it displaces

A sinking object pushes aside its own volume of water. Fill the eureka can to the spout, then lower the object in and collect the water that overflows in a measuring cylinder: that volume is the object’s volume.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 14.3 to 15.6

14 / Physics required practicalsBoth tiers

How should you read the volume of water in a measuring cylinder?

  1. AFrom above the cylinder, at the top of the meniscus
  2. BAt eye level, from the top of the meniscus
  3. CFrom above, at the bottom of the meniscus
  4. DAt eye level, from the bottom of the meniscus
Show the answer

Answer: D At eye level, from the bottom of the meniscus

Water curves up at the sides of the cylinder. Read the scale level with your eye at the bottom of the curve, the meniscus, so you avoid parallax error.

Checked against AQA GCSE Physics 8463 specification, 8.2.5 Required practical activity 5

15 / Physics required practicalsBoth tiers

Put these steps for finding the density of a liquid in order.

  1. APut an empty measuring cylinder on the balance
  2. BZero the balance
  3. CRead the mass and the volume of the liquid
  4. DPour in some of the liquid
Show the answer

The right order:

  1. Put an empty measuring cylinder on the balance
  2. Zero the balance
  3. Pour in some of the liquid
  4. Read the mass and the volume of the liquid

Zeroing the balance with the empty cylinder on it means the reading is the mass of the liquid alone. Read the volume from the cylinder, then density = mass ÷ volume.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 14.3 to 15.6

16 / Physics required practicalsBoth tiers

Air bubbles stick to a stone when it is put in the water. What does this do to the density you work out?

  1. AMakes it too large
  2. BMakes it too small
  3. CMakes it exactly double
  4. DMakes no difference to it
Show the answer

Answer: B Makes it too small

Bubbles add their own volume, so the measured volume is too big and density = mass ÷ volume comes out too small. A splash throws water out that is never collected, so the volume is too small instead.

Checked against AQA GCSE Physics 8463 specification, 8.2.5 Required practical activity 5

17 / Physics required practicalsBoth tiers

A mass in grams and a volume in cm³ give a density in:

  1. Acm³/g
  2. Bg/cm³
  3. Ckg/m³
  4. Dg × cm³
Show the answer

Answer: B g/cm³

Density = mass ÷ volume, so its unit is the mass unit divided by the volume unit. Grams and cubic centimetres give g/cm³; kilograms and cubic metres give kg/m³. 1 cm³ is the same as 1 ml.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 14.3 to 15.6

18 / Physics required practicalsBoth tiers

You hang masses on a spring and measure how far it stretches. What is the independent variable?

  1. AThe length of the ruler beside the spring
  2. BThe extension of the spring
  3. CThe height of the clamp stand
  4. DThe force (weight) on the spring
Show the answer

Answer: D The force (weight) on the spring

You choose the weight hung on the spring, so force is the independent variable. The extension is what you measure. The same spring is used throughout, so its own properties are controlled.

Checked against AQA GCSE Physics 8463 specification, 8.2.6 Required practical activity 6

19 / Physics required practicalsBoth tiers

How is the extension of the spring found?

  1. ANew length plus original length
  2. BNew length minus original length
  3. CThe new length on its own
  4. DNew length divided by original length
Show the answer

Answer: B New length minus original length

Extension is how much longer the spring has become. Measure the original length with no masses, then subtract it from each new length. Using the new length as the extension is a common mistake.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 14.3 to 15.6

20 / Physics required practicalsBoth tiers

Why should you read the pointer on the spring with your eye level with it?

  1. ATo make the spring stretch evenly
  2. BTo keep the masses from swinging
  3. CTo stop the spring overheating
  4. DTo avoid parallax error
Show the answer

Answer: D To avoid parallax error

Looking at the scale from above or below makes the pointer seem to line up with the wrong mark. Reading at eye level, at the same point on the spring each time, avoids this parallax error.

Checked against AQA GCSE Physics 8463 specification, 8.2.6 Required practical activity 6

21 / Physics required practicalsBoth tiers

What is a sensible safety precaution in the spring practical?

  1. AKeep the spring away from water
  2. BWear gloves because the spring gets hot
  3. CWear eye protection
  4. DWork inside a fume cupboard
Show the answer

Answer: C Wear eye protection

An overloaded spring can snap or spring off its hook, and falling masses can hurt feet. Wear eye protection, add masses gently, keep feet clear and stop the stand from tipping over.

Checked against OCR Twenty First Century Physics B J259 specification, P6.3 material under stress

22 / Physics required practicalsBoth tiers

What does a straight line through the origin on a force-extension graph show?

  1. AExtension is inversely proportional to force
  2. BExtension is directly proportional to force
  3. CExtension does not depend on force
  4. DThe spring is past its limit of proportionality
Show the answer

Answer: B Extension is directly proportional to force

Up to the limit of proportionality, doubling the force doubles the extension, so the graph is a straight line through the origin. Beyond it the line curves and the spring may not return to its original length.

Checked against AQA GCSE Physics 8463 specification, 8.2.6 Required practical activity 6

23 / Physics required practicalsBoth tiers

On a graph of force (vertical) against extension (horizontal), the gradient of the straight part gives:

  1. AThe spring constant
  2. BThe weight of the spring
  3. CThe work done
  4. DThe elastic limit
Show the answer

Answer: A The spring constant

Force = spring constant × extension, so force ÷ extension, the gradient, is the spring constant in N/m. A stiffer spring gives a steeper line.

Checked against OCR Twenty First Century Physics B J259 specification, P6.3 material under stress

24 / Physics required practicalsBoth tiers

Put these steps for the spring practical in order.

  1. AHang one mass on the spring
  2. BMeasure the new length
  3. CAdd another mass and measure again
  4. DMeasure the original length of the spring
  5. EClamp the spring and a ruler to a stand
Show the answer

The right order:

  1. Clamp the spring and a ruler to a stand
  2. Measure the original length of the spring
  3. Hang one mass on the spring
  4. Measure the new length
  5. Add another mass and measure again

Set up first, then take the unstretched length before any mass goes on. Add masses one at a time, measuring the length to the same point each time, and work out each extension.

Checked against AQA GCSE Physics 8463 specification, 8.2.6 Required practical activity 6

25 / Physics required practicalsBoth tiers

Why are light gates better than a stopwatch for timing the trolley?

  1. AThey make the trolley go faster
  2. BThey reduce friction on the trolley
  3. CThey remove human reaction time
  4. DThey measure the mass as well
Show the answer

Answer: C They remove human reaction time

A person starting and stopping a stopwatch adds a reaction time that varies each go. A light gate times how long the card blocks its beam; card length ÷ that time gives the speed.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 2.19 to 10.17

26 / Physics required practicalsBoth tiers

Why is a lamp placed above the ripple tank?

  1. ATo power the vibrating bar
  2. BTo make the waves taller
  3. CTo cast shadows of the waves onto paper below
  4. DTo warm the water so the waves move faster
Show the answer

Answer: C To cast shadows of the waves onto paper below

The ripples act like lenses, so the light makes bright and dark lines on the paper or screen below. The shadows are easier to see and measure than the ripples themselves.

Checked against AQA GCSE Physics 8463 specification, 8.2.8 Required practical activity 8

27 / Physics required practicalsBoth tiers

Why do you measure across ten waves and divide by ten to find the wavelength?

  1. AIt means no ruler is needed
  2. BIt changes the frequency of the waves
  3. CIt reduces the uncertainty in each wavelength
  4. DIt makes the waves travel faster
Show the answer

Answer: C It reduces the uncertainty in each wavelength

One wavelength is short and the waves keep moving, so a single measurement is uncertain. Measuring a long run of waves, on a photo or with a stroboscope that freezes them, then dividing, gives a better value.

Checked against AQA GCSE Physics 8463 specification, 8.2.8 Required practical activity 8

28 / Physics required practicalsBoth tiers

How can you find the frequency of the water waves?

  1. AMeasure the distance between two crests
  2. BMeasure the depth of the water
  3. CTime one wave crossing the whole width of the tank
  4. DCount waves passing a point in 10 s, divide by 10
Show the answer

Answer: D Count waves passing a point in 10 s, divide by 10

Frequency is the number of waves passing a point each second. Wave speed = frequency × wavelength. You can check it by timing one wave over a measured distance.

Checked against OpenStax Physics, 13.2 Wave properties

29 / Physics required practicalsBoth tiers

Why must the water be the same depth all over the tank?

  1. ADeep water stops the lamp working
  2. BThe speed of water waves depends on depth
  3. CShallow water cannot carry waves
  4. DThe ruler only works at one depth
Show the answer

Answer: B The speed of water waves depends on depth

Water waves slow down in shallower water, so an uneven depth gives different speeds and wavelengths across the tank. Water and electricity together are a hazard, so keep the tank level and mop up spills at once.

Checked against OCR Twenty First Century Physics B J259 specification, P1.3 How do waves behave?

30 / Physics required practicalsBoth tiers

A small cork floating on the ripple tank bobs up and down but does not move along with the waves. What does this show?

  1. AThe cork stops the wave
  2. BWater waves are longitudinal
  3. CThe water travels with the wave
  4. DThe wave travels, not the water
Show the answer

Answer: D The wave travels, not the water

The water only moves up and down as each ripple passes, so the cork stays in roughly the same place. Waves transfer energy from place to place without carrying the water along.

Checked against OCR Twenty First Century Physics B J259 specification, P1.3 How do waves behave?

31 / Physics required practicalsBoth tiers

Why is a narrow slit put in front of the ray box?

  1. ATo give a thin ray that is easy to mark
  2. BTo change the colour of the light
  3. CTo make the light brighter
  4. DTo stop the light refracting
Show the answer

Answer: A To give a thin ray that is easy to mark

A thin ray lets you mark its centre accurately. Angles are measured from the normal, a line drawn at 90° to the surface where the ray meets it, using a protractor.

Checked against Pearson Edexcel GCSE Physics 1PH0 specification, Appendix 6 core practicals 2.19 to 10.17

32 / Physics required practicalsBoth tiers

How do you record the path of a ray on paper?

  1. AShade in the whole width of the ray with pencil
  2. BPhotograph the ray box from above
  3. CDraw round the ray box
  4. DMark crosses on the ray, then join them
Show the answer

Answer: D Mark crosses on the ray, then join them

Marking two crosses far apart along the centre of the ray, then joining them with a ruler, fixes the direction of the ray well. Crosses close together let a small slip change the angle a lot.

Checked against AQA GCSE Physics 8463 specification, 8.2.9 Required practical activity 9

33 / Physics required practicalsBoth tiers

Light passes from air into a glass block at an angle. Which way does it bend?

  1. AAway from the normal
  2. BAlong the surface
  3. CBack the way it came
  4. DTowards the normal
Show the answer

Answer: D Towards the normal

Light slows down as it enters glass, so a ray hitting at an angle bends towards the normal. It speeds up again as it leaves, so it bends away from the normal.

Checked against OpenStax Physics, 16.2 Refraction

34 / Physics required practicalsBoth tiers

A ray enters the glass block along the normal. What happens?

  1. AIt bends towards the normal
  2. BIt is all reflected back
  3. CIt goes straight on without bending
  4. DIt bends away from the normal
Show the answer

Answer: C It goes straight on without bending

A ray along the normal still slows down in the glass, but because it meets the surface head on it does not change direction. That is why angles of incidence of 0° give no bending.

Checked against OpenStax Physics, 16.2 Refraction

35 / Physics required practicalsBoth tiers

What is the main hazard from the ray box?

  1. AIts light can melt the glass block
  2. BIt gives out harmful gamma rays from the bulb
  3. CIt has mains voltage at the slit
  4. DIts lamp housing gets hot enough to burn
Show the answer

Answer: D Its lamp housing gets hot enough to burn

Drawing round the block lets you put it back and join the ray through it. The ray box bulb runs hot, so let it cool before moving it, and work in a dimmed room with bags tucked away so nobody trips.

Checked against OCR Gateway Physics A J249 specification, P5.1 reflection and refraction (PAG P8)

36 / Physics required practicalsBoth tiers

A measurement is accurate when it is:

  1. AClose to the other repeats
  2. BGiven to many decimal places
  3. CClose to the true value
  4. DTaken with a digital meter
Show the answer

Answer: C Close to the true value

Accurate means close to the true value. Precise means the repeats have little spread. Readings can be precise but not accurate, for example when a meter has a zero error.

Checked against OpenStax Physics, 1.3 The language of physics: accuracy, precision and uncertainty

37 / Physics required practicalsBoth tiers

The resolution of a measuring instrument is:

  1. AThe largest value it can read
  2. BHow close it reads to the true value
  3. CHow long it takes to give a reading
  4. DThe smallest change it can show
Show the answer

Answer: D The smallest change it can show

Resolution is the smallest change in a quantity that the instrument shows. A thermometer reading to 0.1 °C picks up smaller temperature changes than one reading to 1 °C.

Checked against OCR Twenty First Century Physics B J259 specification, Ideas about Science IaS1

38 / Physics required practicalsBoth tiers

Repeating readings and calculating a mean reduces the effect of:

  1. ASystematic errors
  2. BRandom errors
  3. CZero errors
  4. DA wrongly marked scale
Show the answer

Answer: B Random errors

Random errors scatter readings either side of the true value, so averaging repeats reduces their effect. A systematic error shifts every reading the same way, so repeating does not remove it; check or recalibrate the instrument.

Checked against AQA GCSE Physics 8463 specification, 3 Working scientifically, WS 3.7

39 / Physics required practicalsBoth tiers

Before any weight is hung on it, a newtonmeter reads 0.2 N. This is:

  1. AA parallax error
  2. BAn anomalous result
  3. CA random error
  4. DA zero error
Show the answer

Answer: D A zero error

A zero error is a reading when the true value is zero. It is a systematic error, so either reset the meter to zero before starting or take the zero reading away from every result.

Checked against AQA GCSE Physics 8463 specification, 3 Working scientifically, WS 3.7

40 / Physics required practicalsBoth tiers

Parallax error happens when:

  1. AA scale is read from an angle
  2. BA meter is not set to zero
  3. CReadings are not repeated
  4. DThe scale has large divisions
Show the answer

Answer: A A scale is read from an angle

If your eye is not level with the mark, the pointer or liquid seems to line up with a different value. Always read scales, such as a ruler beside a spring or a measuring cylinder, at eye level.

Checked against OpenStax Physics, 1.3 The language of physics: accuracy, precision and uncertainty

02 / Longer answersMarked by levels

6-mark questions on this topic

Write your answer first, on paper. Then open it and tick off the points you made. How 6-mark questions are marked.

6 marks / Specific heat capacity of a metalBoth tiers

You have a 1 kg aluminium block with two holes drilled in it, an electric immersion heater, a thermometer, a joulemeter, a balance and some insulating material.

Describe how you would use this apparatus to find the specific heat capacity of aluminium.

What a full answer includes
  • Check the mass of the block on the balance, in kilograms.
  • Put the heater in one hole and the thermometer in the other, with a few drops of water in the thermometer hole for good thermal contact.
  • Wrap the block in insulation so that less energy is transferred to the surroundings.
  • Record the starting temperature, then connect the heater to the power supply through the joulemeter and switch on.
  • Heat for a fixed time, about 10 minutes, taking care not to touch the hot heater or block.
  • Switch off, read the energy transferred from the joulemeter and record the highest temperature the block reaches.
  • Find the temperature rise by subtracting the starting temperature from the highest temperature.
  • Specific heat capacity is the energy transferred divided by (mass × temperature rise).
  • Let the block cool, repeat the experiment and find a mean value.

Model answer

First I would check the mass of the aluminium block on the balance. I would put the immersion heater into one hole and the thermometer into the other, adding a few drops of water to the thermometer hole so that it makes good thermal contact with the block. I would wrap the block in insulation to reduce the energy transferred to the surroundings. I would record the starting temperature, then connect the heater to the power supply through the joulemeter and switch it on. After heating for about 10 minutes I would switch off, read the energy transferred from the joulemeter and record the highest temperature reached, because the temperature keeps rising for a short time after the heater is switched off. The heater and the block get hot, so I would not touch them. I would subtract the starting temperature to find the temperature rise, then calculate the specific heat capacity by dividing the energy transferred by the product of the mass and the temperature rise. Finally I would let the block cool, repeat the experiment and find a mean.

Where marks slip

Many answers leave the block uninsulated, so energy escapes to the surroundings and the value found is too high. Repeating does not make a result more accurate; say you repeat to find a mean and spot anomalies.

6 marks / Current and potential difference for a lampBoth tiers

Describe how you would investigate how the current through a filament lamp depends on the potential difference across it, and how you would use your results.

What a full answer includes
  • Connect the power supply, a variable resistor, an ammeter and the filament lamp in series.
  • Connect a voltmeter in parallel across the lamp.
  • Use the variable resistor to set the potential difference across the lamp and record the current shown on the ammeter.
  • Change the potential difference in equal steps to get about eight pairs of readings.
  • Reverse the connections to the power supply and repeat to get readings for negative potential differences.
  • Repeat each set of readings and work out a mean current for each potential difference.
  • Plot a graph of current against potential difference.
  • Work out the resistance at each point by dividing the potential difference by the current.
  • The graph is a curve because the filament gets hotter as the current increases, so its resistance increases.

Model answer

I would connect the power supply, a variable resistor, an ammeter and the filament lamp in series, and connect a voltmeter in parallel across the lamp. Using the variable resistor I would set a small potential difference across the lamp and record the current shown on the ammeter. I would then increase the potential difference in equal steps, recording the current each time, to get about eight pairs of readings. Next I would reverse the connections to the power supply and take the same readings again, so that I also have negative values. I would repeat the whole set of readings and calculate a mean current for each potential difference. The lamp gets hot, so I would not touch it. I would plot a graph of current against potential difference and work out the resistance at each point by dividing the potential difference by the current. The graph is a curve, not a straight line, because as the current increases the filament gets hotter and its resistance increases, so the current rises less and less for each extra volt.

Where marks slip

The voltmeter goes in parallel across the lamp and the ammeter in series; swapping them is a common slip. Also explain the curve: the filament heats up, so its resistance increases.

6 marks / Density of an irregular objectBoth tiers

You are given a small stone with an irregular shape, a top-pan balance, a displacement (eureka) can, a measuring cylinder, some thread and water.

Describe a method to find the density of the stone.

What a full answer includes
  • Measure the mass of the stone on the top-pan balance.
  • Fill the displacement can with water until it overflows, and wait until it stops dripping from the spout.
  • Put the empty measuring cylinder under the spout.
  • Lower the stone gently into the can on the thread until it is completely under the water, without splashing.
  • The volume of water collected in the measuring cylinder is equal to the volume of the stone.
  • Read the measuring cylinder at eye level, from the bottom of the meniscus.
  • Calculate the density by dividing the mass by the volume, for example in g/cm³.
  • Repeat the measurements and find a mean.

Model answer

First I would measure the mass of the stone using the top-pan balance. Because the stone has an irregular shape, I cannot work out its volume from its dimensions, so I would use displacement. I would fill the displacement can with water until it overflows and wait until no more water drips from the spout. Then I would put an empty measuring cylinder under the spout and tie the thread to the stone. I would lower the stone gently into the can until it is completely under the water, without splashing, so that the water it pushes out runs into the measuring cylinder. The volume of water collected is equal to the volume of the stone. I would read the measuring cylinder at eye level from the bottom of the meniscus. I would calculate the density by dividing the mass by the volume, giving an answer in g/cm³, which I could convert to kg/m³. I would dry the stone, repeat the measurements and find a mean density.

Where marks slip

A common mistake is forgetting to fill the can to the spout before the stone goes in, so the water collected is less than the stone’s volume. An irregular object cannot be measured with a ruler; use displacement.

6 marks / Force and extension of a springBoth tiers

Plan an investigation to find how the extension of a spring depends on the force stretching it.

What a full answer includes
  • Hang the spring from a clamp on a stand, with a metre ruler clamped upright beside it, and clamp the stand to the bench so it cannot topple.
  • Measure the length of the spring with no load, reading the ruler at eye level against a fixed point such as a pointer on the bottom of the spring.
  • Hang a mass hanger on the spring and add slotted masses one at a time, for example 100 g each time.
  • After adding each mass, measure the new length of the spring.
  • Work out the extension each time by subtracting the original length from the new length.
  • The force is the weight of the masses, found from mass multiplied by gravitational field strength.
  • Wear eye protection and keep feet away from under the masses in case the spring snaps or the masses fall.
  • Repeat the readings, for example while taking the masses off again, and find a mean extension for each force.
  • Plot force against extension: a straight line through the origin shows the extension is directly proportional to the force, up to the limit of proportionality.

Model answer

I would hang the spring from a clamp on a stand and clamp a metre ruler upright beside it, with the stand clamped to the bench so that it cannot topple. I would measure the length of the spring with nothing on it, reading the ruler at eye level against a pointer fixed to the bottom of the spring. Then I would hang a mass hanger on the spring and add 100 g masses one at a time, measuring the new length after each one. I would work out each extension by subtracting the original length from the new length. The force on the spring is the weight of the masses, which I would find by multiplying the mass in kilograms by the gravitational field strength. I would wear eye protection and keep my feet clear in case the spring snaps. I would repeat the readings while removing the masses and find a mean extension for each force. Finally I would plot force against extension; a straight line through the origin shows that extension is directly proportional to force up to the limit of proportionality.

Where marks slip

The most common slip is plotting the total length of the spring instead of its extension. Subtract the original length every time, or the line will not pass through the origin.

6 marks / Force and acceleration of a trolleyBoth tiers

A trolley on a long bench is pulled by a string. The string passes over a pulley at the end of the bench to a hanger carrying slotted masses.

Plan an investigation to find how the acceleration of the trolley depends on the resultant force on it.

What a full answer includes
  • Fix a card of known length on the trolley and set up two light gates along the bench, connected to a data logger.
  • Release the trolley from rest from the same starting point each time.
  • The data logger uses the light gates to find the speed at each gate and the time between them, so acceleration is the change in velocity divided by the time taken.
  • The force pulling the trolley is the weight of the hanger and its masses.
  • Change the force by moving one slotted mass at a time from the trolley to the hanger.
  • Moving masses this way keeps the total mass being accelerated the same, so only the force changes.
  • Tilt the bench slightly so the trolley keeps a steady speed when given a push, to make up for friction.
  • Put something soft under the hanger and stop the trolley before it hits the pulley; repeat each force and find a mean acceleration.
  • Plot acceleration against force: a straight line through the origin shows that acceleration is directly proportional to the resultant force.

Model answer

I would start with all but one of the slotted masses on the trolley and one on the hanger. I would fix a card of known length on top of the trolley and set up two light gates along the bench, connected to a data logger. I would tilt the bench slightly so that the trolley moves at a steady speed when given a push, to make up for friction. Then I would release the trolley from rest from the same point each time. The data logger uses the time the card takes to pass each gate to find the speed there, and the time between the gates, so the acceleration is the change in velocity divided by the time taken. The force pulling the trolley is the weight of the hanger and its masses. To change the force, I would move one mass at a time from the trolley to the hanger, which keeps the total mass the same so that only the force changes. I would put something soft under the hanger for safety and repeat each force three times to find a mean acceleration. A graph of acceleration against force that is a straight line through the origin shows they are directly proportional.

Where marks slip

Adding extra masses to the hanger without taking them off the trolley changes the total mass as well as the force. Moving masses from the trolley to the hanger keeps the mass constant, so it is a fair test.

6 marks / Measuring waves in a ripple tankBoth tiers

Describe how you would use a ripple tank to find the frequency, wavelength and speed of water waves.

What a full answer includes
  • Put a shallow layer of water of even depth in the tank and use a vibrating bar driven by a motor to make straight waves.
  • Switch on a lamp above the tank so that the wave pattern shows on a sheet of paper or a screen below it.
  • Use a low frequency, so that the waves can be counted.
  • Count the number of waves passing a point in 10 seconds and divide by 10 to find the frequency in hertz.
  • Place a ruler on the paper at right angles to the waves, measure the length across ten waves and divide by ten to find the wavelength.
  • Taking a photograph of the pattern with the ruler in view makes the moving waves easier to measure.
  • Calculate the wave speed by multiplying the frequency by the wavelength.
  • Check the speed by timing one wave across a measured distance and dividing the distance by the time.
  • Repeat each measurement and find a mean.

Model answer

I would pour a shallow layer of water into the ripple tank, making sure it has the same depth everywhere, and lower a vibrating bar driven by a motor so that it just touches the water and makes straight waves. A lamp above the tank shows the wave pattern on a sheet of paper below. I would set a low frequency so that the waves can be counted. To find the frequency I would count the number of waves passing a mark on the paper in 10 seconds and divide by 10. To find the wavelength I would place a ruler on the paper at right angles to the waves, measure the length across ten waves and divide by ten, which is more accurate than measuring one small, moving wave. Taking a photograph with the ruler in view makes this easier. I would calculate the wave speed by multiplying the frequency by the wavelength. I could check it by timing one wave as it travels a measured distance and dividing the distance by the time. I would repeat each measurement and use mean values.

Where marks slip

Trying to measure one wavelength directly is very hard because the waves are small and moving. Measure across ten waves and divide by ten, or use a photograph.

6 marks / Mass and acceleration of a trolleyBoth tiers

A trolley sits on a runway that is tilted just enough to cancel out friction. A string tied to the trolley runs over a pulley at the lower end to a hanger carrying a few slotted masses, which pulls the trolley. You also have extra slotted masses, a balance, a card, two light gates and a data logger.

Plan an investigation to find how the mass of the trolley affects its acceleration when the force pulling it stays the same.

What a full answer includes
  • Keep the same masses on the hanger throughout, so the pulling force, the weight of the hanger and its masses, stays the same.
  • Check the runway is tilted so that the trolley keeps a steady speed after a small push, which cancels out friction.
  • Measure the mass of the trolley on the balance, then add slotted masses to it in equal steps, finding the total mass each time.
  • Fix a card of known length on the trolley and place two light gates along the runway, connected to the data logger.
  • Release the trolley from rest from the same marked point each time.
  • The data logger finds the speed at each gate and the time between the gates; the acceleration is the change in velocity divided by the time taken.
  • Put something soft under the hanger and a stop at the end of the runway; repeat each mass three times and find a mean acceleration.
  • As the mass increases, the acceleration decreases.
  • A graph of acceleration against 1 ÷ mass (the trolley and hanger together) is a straight line through the origin, so acceleration is inversely proportional to mass.

Model answer

I would keep the same masses on the hanger for the whole investigation, so that the pulling force, which is the weight of the hanger and its masses, stays the same. First I would check that the runway is tilted just enough for the trolley to keep a steady speed after a small push, which cancels out friction. I would measure the mass of the trolley on the balance and fix a card of known length on top of it. I would place two light gates along the runway, connected to a data logger, and release the trolley from rest from the same marked point each time. The data logger uses the time the card takes to pass through each gate to find the speed there, and the time between the gates, so the acceleration is the change in velocity divided by the time taken. I would then add slotted masses to the trolley in equal steps, measuring the total mass each time, and repeat each mass three times to find a mean acceleration. A soft box under the hanger and a stop at the end of the runway keep it safe. As the mass increases, the acceleration decreases, and a graph of acceleration against 1 ÷ mass is a straight line through the origin, showing that acceleration is inversely proportional to mass.

Where marks slip

Changing the masses on the hanger at the same time changes the force as well as the mass, so the test is no longer fair. Remember that a bigger mass gives a smaller acceleration for the same force.

6 marks / Specific heat capacity of waterBoth tiers

You have a beaker, water, an electric immersion heater, a joulemeter, a thermometer, a top-pan balance, a stirrer and some insulating material.

Describe how you would use this apparatus to find the specific heat capacity of water.

What a full answer includes
  • Put the empty beaker on the balance and zero it, then pour in water and record the mass of the water in kilograms.
  • Wrap the beaker in insulation and cover it with a lid, so that less energy is transferred to the surroundings.
  • Put the immersion heater fully under the water before switching it on, so that it does not overheat.
  • Record the starting temperature of the water, then connect the heater to the power supply through the joulemeter and switch on.
  • Stir the water while it is heated, so that it is all at the same temperature.
  • After a set time, such as 10 minutes, switch off, read the energy transferred from the joulemeter and record the highest temperature of the water.
  • Find the temperature rise by subtracting the starting temperature.
  • Specific heat capacity is the energy transferred divided by (mass × temperature rise).
  • Do not touch the heater until it has cooled; repeat the experiment with fresh water and find a mean value.

Model answer

I would put the empty beaker on the balance and zero it, then pour in some water so that the balance shows the mass of the water alone, which I would convert to kilograms. I would wrap the beaker in insulation and put a lid on it to reduce the energy transferred to the surroundings. I would put the immersion heater into the water, making sure it is fully covered before it is switched on, because a heater in air overheats. I would record the starting temperature of the water, then connect the heater to the power supply through the joulemeter and switch it on. While the water is heated I would stir it, so that the thermometer reads the temperature of all the water and not just a hot patch near the heater. After about 10 minutes I would switch off, read the energy transferred from the joulemeter and record the highest temperature reached. I would subtract the starting temperature to find the temperature rise, then calculate the specific heat capacity by dividing the energy transferred by the product of the mass and the temperature rise. The heater stays hot, so I would not touch it until it cools. Finally I would repeat with fresh water and find a mean.

Where marks slip

A common slip is weighing the beaker and water together; zero the balance with the empty beaker so you have the mass of the water alone. Without insulation and a lid, energy escapes and the value found is too high.

03 / In the appComing to Show Working

All 92 practical facts in Show Working

In the app, choose your exam board and course and you only see what your board asks for. Tap through questions, or open Read the answers to see every answer in the topic at once, covered until you tap. Science is coming to the app soon.

Coming soon to the App Store

More GCSE physics topics

EnergyForcesForces and motionWaves in matterLight and electromagnetic wavesElectricityMagnetism and electromagnetismParticle model of matterAtomic structureSpace physicsAll of GCSE Physics

Our own questions, written for every board. Show Working is independent and not affiliated with any exam board.

Show WorkingComing soon to the App Store