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Questions on Electric Circuits

Q17. Imran built a puzzle circuit with three identical bulbs and a 3V battery.

He covered the connections to the bulbs with a piece of card as shown below.

The bulbs could be seen through holes in the card. All the bulbs were on but their brightness was different.

Lucy removed bulbs A, B and C in turn.

Before connecting each bulb back into the circuit she observed the effect on the other two bulbs. She recorded her observations in the table below.

bulb removed

observations

A

B and C stayed on

B

C went off
A stayed on

C

B went off
A stayed on

(a) Complete the circuit diagram below to show how the three bulbs could be connected. Use your knowledge of series and parallel circuits, and the observations in the table to help you.

2 marks

(b) Imran used three identical bulbs but their brightness was different. Which bulb was the brightest (give the letter)? Give the reason for your choice.

2 marks

(c) Imran added a switch to the circuit so that he could turn all three bulbs on and off at the same time. Place a letter S on your circuit diagram where this switch could be placed.

1 mark

Total 5 marks