Simple Circuits (OCR GCSE Physics A (Gateway))

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

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.

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]

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

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]

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

i) What is the name of this component?

[1]

ii) Why is this component needed in this circuit?

[1]

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

The student plots a graph of her results.

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]

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]

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.

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 

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

Look at the results.

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]

The diagram shows an electric car being charged at a charging station.

As the car is charged, a direct potential difference is applied across the car's battery.

Describe what is meant by a direct potential difference.

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 the time it will take to fully charge the car battery.

Use the Equation Sheet.

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

A current of 13 A flows through the circuit.

The battery pack is made up of 167 lithium ion cells connected in series, each with a potential difference of 3.2 V.

Calculate the resistance of the motor.

Use the Equation Sheet.

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

Both the mains supply and the high-speed charging station use a potential difference of 230 V.

Show that charging the car using the high-speed charging station would take one third of the time it would take using the mains supply.

Use the Equation Sheet.