AQA GCSE Physics: Combined Science

Topic Questions

2.1 Current, Potential Difference & Resistance

1a1 mark

Which of the following symbols represents a lamp?

Tick (✓) one box.

2-1-e-1a-option-symbols

1b2 marks

Which of the following is needed in a circuit for charge to flow?

Tick (✓) two boxes.

   

A source of resistance begin mathsize 36px style square end style
A closed circuit loop square
A source of potential difference square
An ammeter square
A variable resistor  square
A lamp square
1c1 mark

Choose the correct equation linking potential difference, current, and resistance.

Tick (✓) one box.

   

V space equals space I R begin mathsize 36px style square end style
V space equals space I over R  square
V space equals space I space plus space R square
V space equals space I squared R square
1d3 marks

Figure 1 shows a simple circuit.

Figure 1

2-1-e-1d-simple-circuit-bulb-ammeter

Calculate the resistance of the bulb.   

   

Resistance = .................................... Ω

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2a2 marks

Which of the following statements is not true about current?

Tick (✓) two boxes.

   

Current has the same value anywhere in a closed loop begin mathsize 36px style square end style
Current is the rate of charge flow square
Current is measured by a voltmeter square
The unit for current is the coulomb square
2b2 marks

Which of the following diagrams shows the correct placement for an ammeter?

Tick (✓) two boxes.

2-1-e-2b-option-graphs

2c4 marks

Complete the sentences. 

Choose answers from the box. 

Each answer can be used once, more than once or not at all.

negative positive neutral

The charge on an electron is  ...............................

   

Electrons flow from the .............................. terminal to the .............................. terminal.

   

Conventional current is the perceived movement of  .............................. charge.

   

Conventional current flows from the  .............................. terminal to the .............................. terminal.

2d1 mark

The unit for charge is the coulomb. Which of the following is the correct equation for charge?

Tick (✓) one box.

   

Q space equals space I over t begin mathsize 36px style square end style
Q space equals fraction numerator space t over denominator I end fraction square
Q space equals space I t  square
Q space equals space I space plus space t square

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3a1 mark

Which of the following is the correct symbol for a battery?

Tick (✓) one box.

2-1-e-3a-option-symbols

3b1 mark

Which instrument is used to measure potential difference?

Tick (✓) one box.

   

 Ammeter begin mathsize 36px style square end style
Joulemeter square
Newtonmeter square
Voltmeter square
3c1 mark

Which of the following diagrams shows the incorrect placement of a voltmeter?

Tick (✓) one box.

2-1--3c-otpion-circuits

3d3 marks

Figure 1 shows a simple series circuit.

Figure 1

2-1-e-3d-simple-circuit-pd

The ammeter shows a reading of 0.5 A.

The resistor is 10 Ω.

Calculate the potential difference across the resistor.   

   

Potential difference = .................................... V

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4a5 marks

Figure 1 shows the equipment used to investigate the resistance of a length of wire at a constant temperature.

Figure 1

2-1-e-4a-resistance-of-a-wire

Table 1 shows the steps the students should follow in order to produce valid results.



Table 1

Connect a wire from the main circuit to the thin resistance wire at 0 cm 1
Repeat the readings of potential difference and current  
Record the potential difference and current  
Repeat at 30 cm, and again at 40 cm on the resistance wire  
Connect a wire from the main circuit to the thin resistance wire at 10 cm  
Move the crocodile clip from 10 cm to 20 cm on the thin resistance wire  
 

Complete the table by numbering the steps in the correct order.

The first step has been completed for you.

4b1 mark
Write out the equation you would use to calculate the resistance (R) from the measurements of potential difference (V) and current (I).
4c2 marks
Name the independent and dependent variables in this investigation.
4d1 mark

A student plots of graph of the data recorded in the investigation.

What shape would you expect the graph to be?

Tick (✓) one box.

 2-1-e-4d-option-graphs

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5a2 marks
Some resistors have a fixed resistance and for some resistors the resistance can vary.



Name two examples of a resistor whose resistance can vary.

5b1 mark

Draw the symbol for a thermistor.

5c2 marks

State two applications of thermistors.

5d3 marks

Complete the sentences. 

Choose answers from the box. 

Each answer can be used once, more than once or not at all.

ohmic

non-ohmic

 

decreases

increases

 

     

Thermistors are .............................. conductors that vary their resistance with temperature.

   

As temperature .............................. the resistance of a thermistor decreases.

   

As temperature .............................. the resistance of a thermistor increases.

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1a3 marks

A student is investigating the I-V characteristic of a filament bulb. Figure 1 shows the circuit they set up to conduct the investigation.

Figure 1

2-1-h-1a-incorrect-circuit

The circuit shown in Figure 1 will not provide valid results.

Describe the errors the student has made and state how to rectify them.

1b2 marks

The student's readings of current at all potential differences were significantly different to those recorded by another student in her class.

Suggest two possible reasons why.

1c4 marks
The student plotted the graph shown in Figure 2 from her data.


Figure 2

2-1-h-1c-iv-characteristics-filament-graph

Explain how the shape of the graph shows that the filament bulb is a non-ohmic conductor.

  

1d1 mark
Use the graph shown in Figure 2 to calculate the resistance of the filament lamp when the potential difference is 3 V.

Give your answer to an appropriate number of significant figures.

   

   

Resistance of filament lamp = .................................... Ω

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2a1 mark
Draw the circuit symbol for a light-dependent resistor (LDR).
2b4 marks
A student is designing an experiment to investigate the resistance of light dependent resistors.

This is the method the student has proposed.

  1. Set up a circuit with a cell, an analogue ammeter, and an LDR in series, with an analogue voltmeter in parallel across the LDR
  2. In a dark room, place a lamp 100 cm away from the LDR and turn it on
  3. Measure the readings of current and potential difference
  4. Move the lamp to 80 cm away and measure the current and potential difference
  5. Repeat at 60 cm, 40 cm, 20 cm, and 0 cm

Suggest two improvements that the student could make and explain how the suggestions would improve the data collected.

2c1 mark
Sketch the shape you would expect an IV graph to be for LDR.
2d1 mark
Explain how the shape of the graph shows that the LDR is a nom-ohmic conductor.

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3a4 marks
Describe the difference between conventional current and electron flow.
3b1 mark

Figure 1 shows the variation in current with potential difference for two components, X and Y.

Figure 1

2-1-h-3b-iv-lamps-graph

X and Y are two variants of the same component.

Name the component.

3c3 marks
State which component in Figure 1 has the greatest resistance. Explain your answer.

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4a1 mark

Figure 1 shows an electric car being charged at a charging station.

Figure 1

2-1-h-4a-electric-car-charging

As the car is being charged, there is a direct potential difference applied across the battery of the car.

Describe what is meant by the term 'direct potential difference'.

4b5 marks

The battery of the electric car can store 2.16 ×108 J of energy.

The power output of the charging station is 6.9 kW.

The battery indicator of the car show it to be at 21% when the car is plugged in.

Determine how long it will take to fully charge the car battery.

   

   

Time required to fully charge = .................................... s
4c3 marks

Figure 2 shows a simplified diagram of the circuit connecting the battery to the motor of the car.

Figure 2

2-1-h-4c-circuit-car

A current of 13 A flows through the circuit.

There are 167 lithium ion cells, each with a potential difference of 3.2 V, are connected in series to form the battery pack. 

Calculate the resistance of the motor.

   

Resistance = .................................... Ω
4d1 mark

A charging station can provide a current of 50 A.

Charging an electric vehicle with a three-point plug from a residential mains supply provides 10 A of current.

Both methods use a potential difference of 230 V.

How does the time taken to charge the battery with the high speed charging station compare with the time taken using the mains supply?

Tick (✓) one box.

   

The mains supply is 5 times faster begin mathsize 36px style square end style
The charging station takes 1⁄5 of the time size 36px square
The mains supply is slower by a factor of 4 size 36px square
The charging station is faster by a factor of 0.5  size 36px square

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5a2 marks

Figure 1 shows two torches. Torch A uses a filament lamp. Torch B uses an LED.

Figure 1

2-1-h-2a-torches

Both torches contain a switch and three cells.

Write A in the box that shows the correct diagram for Torch A.

Write B in the box that shows the correct diagram for Torch B.

 2-1-h-5a-option-circuits

5b5 marks

The current flowing through Torch A is 45 mA.

The charge flow through the battery is 740 C.

Calculate how long the torch will work for before the cells need replacing.

Give your answer to the nearest minute.

   

   

Time = .................................... minutes
5c5 marks

The total power input for both torches is 0.22 W.

The useful power output of the LED is 0.17 W.

The ratio of efficiency of Torch B to Torch A is 3:1.

Calculate the useful power output of Torch A.

   

   

Useful power output of Torch A = .................................... W
5d2 marks

Write A in the box that shows the correctly shaped graph for Torch A.

Write B in the box that shows the correctly shaped graph for Torch B.

 2-1-h-5-d-options-graph-table

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1a1 mark

Figure 1 shows a graph of current against potential difference for a circuit component

Figure 1

fig-1-2-1-medium-aqa-gcse-physics

What is the name of the component?
1b3 marks
Explain how the resistance of the component changes as the potential difference across it increases.
1c1 mark
LED lamps are considerably more energy efficient than the old filament bulbs that can be found in many houses.

What does 'more energy efficient' mean?

1d3 marks

It is useful to be able to detect temperature, and then to turn on a heater when it gets cold.

A thermistor is a component that allows us to do this.

Part of a control circuit for doing this is shown in Figure 2.

Figure 2

fig-2-q1-2-1-medium-aqa-gcse-physics

The temperature decreases.

What happens to the resistance of the thermistor, the current through the thermistor and the potential difference across it?

Resistance ___________________ Ω

Potential difference ___________________

Current ___________________

1e2 marks

What is the resistance of the thermistor when the potential difference across it is 3 V?

Give a reason for your answer.

Explain your answer.

1f4 marks

Calculate the current through the thermistor when the resistance of the thermistor is 5000 Ω.

Give your answer to 2 significant figures.

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2a1 mark

The diagram in Figure 3 below shows a sensing circuit which is used to control a set of automatic lights.

Figure 3

PBL7k_fW_fig-3-2-1-medium-aqa-gcse-physics

What quantity is measured by the voltmeter?
2b1 mark
Add an ammeter to the diagram which could measure the current through the LDR.
2c3 marks

When the potential difference across the LDR is 6.4 V, the current in the circuit is 4.8 mA.

Calculate the resistance of the LDR.

2d2 marks
Explain why the potential difference across the thermistor changes as the temperature in the house decreases.
2e3 marks
The circuit is left to run for 10 minutes. Calculate the charge that flows in 10 minutes when the current in the circuit is 4.8 mA

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3a3 marks

A student investigated how current varies with potential difference for two different resistors.

Her results are shown in Figure 4 below.

Figure 4

fig-4-2-1-medium-aqa-gcse-physics

Complete the circuit diagram for the circuit that the student could have used to obtain the results shown in the figure above.
q3-2-1-medium-aqa-gcse-physics

3b2 marks
Resistor 2 has the higher resistance.



Explain how this is shown by the graph above in
Figure 4.

3c2 marks

Both resistors behave like ohmic conductors for the full range of potential differences used in this investigation.

Explain what an ohmic conductor is.

3d2 marks
Use the graph above in Figure 4 to calculate the resistance of both resistor 1 and resistor 2.
3e1 mark

Resistor 1 and resistor 2 are placed in series with each other.

Calculate the Total resistance of this combination.

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4a1 mark

Thermistors can be used as digital thermometers if their resistance is known at a variety of different temperatures.
 
The apparatus required to obtain the data necessary to carry out this calibration is shown in Figure 5 below.

Figure 5

fig-5-2-1-medium-aqa-gcse-physics

In the space below, draw the circuit symbol for a thermistor.
4b2 marks
Calculate the resistance of the thermistor at 15℃, using the data from Figure 5
4c1 mark
Complete the sketch graph in Figure 6 below to show how the resistance of a thermistor changes between the temperatures of 15 ℃ and 100 ℃.

Figure 6

fig-6-2-1-medium-aqa-gcse-physics

4d1 mark
Give an example of a device that could include a thermistor
4e1 mark

Ammeters, which are used in circuits have very low resistances.

Why is it important that ammeters have a very low resistance?

4f2 marks

A student plans to change the experiment in Figure 6 to investigate how the resistance of an LDR changes with the intensity of light shone on it.

Once change the student makes is to replace the thermistor with an LDR. 

Suggest two further changes the student should make to the apparatus.

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5a4 marks

Some students are investigating the I-V characteristics of a fixed resistor.

The students are given the following equipment:
    • An ammeter
  • A voltmeter
  • A variable resistor
  • Fixed resistors of 100 Ω, 200 Ω, 400  and 500 Ω
  • A power pack
  • Wires

Draw a circuit using the equipment from the list that would enable the students to gather valid data.

5b5 marks
Describe a method that would allow the students to obtain valid results.
5c1 mark
The students plotted their data and produced the graph shown in Figure 1.



Figure 1

2-1-m-5c-iv-characteristics-graph

Write down an expression for the gradient of the graph in terms of resistance.

5d4 marks
Use the graph to determine the resistance of the fixed resistor used by the students.

   

   

Resistance = .................................... Ω

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