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GCSE Standard Questions: Electric Circuits

Q13.

(a) Clark investigated how the current in a circuit varied with the number of lamps box connected in parallel in the circuit. The diagram below shows the circuit with three identical lamps connected in parallel.

And here is the graph of his results:

(i) Complete the sentence below by choosing a word/phrase from the box as your answer - each one can be used once, more than once or not at all.

decreased stayed the same increased

 

As the number of lamps increased , the current increased, the total resistance of the circuit decreased and the potential difference across the battery stayed the same.

[3 marks]

(ii) When there were three lamps in the circuit the digital ammeter reading kept changing between 0.35 A and 0.36 A.

What type of error would this lead to?

A random error

[1 mark]

(b) The diagram below shows a circuit with five ammeters and three identical lamps.

(i) Complete the table below and give the readings that you would expect to see on ammeters A2 and A5

Ammeter
A1
A2
A3
A4
A5

Current in amps

 

0.36

 

0.12

0.12

 

0.12

 

0.36

 

[2 marks]

(ii) The resistance of one lamp is 15 Ω.

If the current flowing through the lamp is 0.12 A, calculate the power output of the lamp.

State the power output to the correct number of significant figures.

P = IV

V = IR

P = I2R

P = 0.122 x 15

P = 0.216

P = 0.22 W

Values are given to 2sf so the calculated answer should only be quoted to that number of sf too.

[3 marks]

(Total 9 marks)