Simple Circuits (OCR Gateway GCSE Physics: Combined Science)

Topic Questions

1a4 marks

A student sets up a circuit to find out the resistance of an unknown resistor. The student makes three mistakes in their circuit.


Look at the circuit diagram of their experiment.

q17-paper1-june2098-ocr-gcse-physics

i)
Write down the three mistakes the student makes.

1 ..................................................................

2 ..................................................................

3 ..................................................................
[3]


ii)
For one of the mistakes identified in (a)(i) describe how the student can fix the error.

[1]
1b4 marks

The student finds that the current is 20 mA when the potential difference is 4.0 V.


Calculate the resistance of the unknown resistor.


Include the unit for resistance in your answer.


Use the equation: resistance = potential difference ÷ current.


Resistance = ........................................ Unit = ............... 

1c3 marks

Calculate the charge that flows when a current of 2.5 A flows for 30 seconds.

Charge = ..................................................... C 

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2a9 marks

A student sets up the circuit in Fig. 17.1 to investigate the resistance of a lamp.

fig-17-1-paper1-oct-nov2020-ocr-gcse-physics

Fig. 17.1

i)
The student also needs to add a voltmeter to the circuit.

On Fig. 17.1 draw where the voltmeter should be connected.

[2]

ii)
The student takes readings of potential difference and current and records them in Table 17.1.

Potential difference (V) Current
1.0 1.000
2.0 1.9
3.0 2.7
4.0 3.2
5.0 3.5

Table 17.1


There are two mistakes in the results table.

Write down the two mistakes and suggest how they could be corrected.

Mistake 1: ................................................................


Correction 1: ............................................................


Mistake 2: ................................................................

Correction 2: ............................................................



[4]

iii)
Calculate the resistance of the lamp when the potential difference is 4.0 V in Table 17.1.

Use the equation: potential difference = current × resistance

Resistance = ..................................................... Ω [3]

2b8 marks

The student plots the results from Table 17.1 on the graph in Fig. 17.2.

fig-17-2-paper1-oct-nov2020-ocr-gcse-physics

Fig. 17.2

i)

Plot the missing point at 1.0 V on the graph and draw a line of best fit.

[2]

ii)

Describe the relationship between potential difference and current.

Use data from the graph to support your answer.

 [2]

iii)

Explain how you could use the circuit in Fig. 17.1 to investigate the resistance of a fixed resistor instead of a lamp.

 [2]

iv)
Explain how and why the graph in Fig. 17.2 would look different for a fixed resistor at a constant temperature.

 [2]

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3a2 marks

A student builds a circuit to investigate the resistance of component X.

q16-paper3-june2018-ocr-gcse-physics

i)

What is the name of this component?

q16ai-paper3-june2018-ocr-gcse-physics

[1]

ii)
Why is this component needed in this circuit?

[1]

3b4 marks

The student uses the circuit to take current and potential difference readings.

The student plots a graph of her results.

q16b-paper3-june2018-ocr-gcse-physics

i)
Look at the graph. What is component X in the circuit?
[1]
ii)
The resistance of component X varies as the potential difference changes.

Describe how the graph shows this and explain why this happens.

[3]

3c5 marks

Component X has a resistance of 16 Ω when a current of 0.25 A flows.

i)
Calculate the potential difference across component X.

Use the equation: Potential difference = Current × Resistance

Answer = .........................V [2]

ii)
Calculate the power of component X when a current of 0.25 A flows.

Answer = .........................W [3]

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4a3 marks

A student finds a resistor which has no markings on it.

The student uses a voltmeter, an ammeter and a cell to find the resistance of the resistor.

Draw a circuit diagram to show how the student could set up this apparatus to find the resistance of the resistor.

4b3 marks

In the experiment the current is 0.15 A and the potential difference is 2.0 V.

potential difference = current × resistance


Calculate the resistance of the unknown resistor.

Show your working.

Record your answer to 3 significant figures.

Answer = ........................... Ω 

4c2 marks

The student repeats the experiment with different potential differences and currents.

Look at the results.

Potential
difference
(V)
Current
(A)
(Attempt 1)
Current
(A)
(Attempt 2)
Current
(A)
(Attempt 3)
Mean
current
(A)
2.0 0.15 0.14 0.16 0.15
4.0 0.31 0.31 0.31 0.31
6.0 0.44 0.44 0.38 0.44
8.0 0.60 0.62 0.58 0.60
10.0 0.74 0.75 0.73 0.74

There is an anomaly in the results.

i)
Write down the anomaly from the table.

[1]

ii)
How did the student deal with the anomaly.

[1]

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