A circuit contains three resistors connected in series to a ideal battery

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

A circuit contains three resistors connected in series to a

12\,\text{V}

ideal battery. At

20^{\circ}\text{C}

their resistances are

10\,\Omega

20\,\Omega

and

30\,\Omega

. The first two resistors have a temperature coefficient of resistance

\alpha = 0.004\,^{\circ}\text{C}^{-1}

while the third has

\alpha = 0.002\,^{\circ}\text{C}^{-1}

. If the temperature of the entire circuit rises uniformly to

50^{\circ}\text{C}

, the percentage change in the circuit current is closest to (a) decreases by about

12\%

(b) increases by about

8\%

8\%

(d) decreases by about

4\%