Question

Rahima was investigating a circuit for her school project. She wanted to demonstrate the effect of length on the resistance of a conductor. The following is the given circuit with resistors A and B that are made of the same metal and the same thickness but ‘A’ is twice as long as ‘B’. The total current in the circuit is 6 A and the Voltage of the battery is 12 V.

(a) What will be the resistance in the circuit?  

(b) Determine the value of ‘RA’ and ‘RB’.

(c) Determine the current in both the ammeters. Will the current in ‘A1 ‘and ‘A2’ be the same? Justify your answer.

Answer 1

(a) R = V/I  

R = 12/6

R = 2 Ω  

(b) R_A = 12/2

 = 6Ω

R_B = 12/4

 = 3 Ω

(c) For the given circuit, R α l and R α 1/I

The resistance of ‘A’ is twice that of ‘B’ and so the current in both will not be the same but in the ratio of 1:2, so the current in ‘A’ will be 2A and that in ‘B’ will be 4A.

I_A = V/R_A = 12 / 6 = 2 A

I_B = V/R_B = 12/3 = 4 A