Question

A electric lamp of resistance 20 ohms and a resistor of 4 ohms connected to a 12 volt battery
Find the potential difference and current through the circuit

Answer 1

Answer:

(a) The resistance of the electric lamp R1 = 20 Ω.

The resistance of the conductor connected in series R2 = 4 Ω.

The total resistance in the circuit

R = R1 + R2

R = 20 Ω + 4 Ω = 24 Ω

(b) The total potential difference across the two terminals of the battery V = 6 V.

By Ohm's law, the current through the circuit is given by

I = V/R

= 6 V/24

= 0.25 A

(c) On applying Ohm's law to the electric lamp and resistor separately, we get potential difference across the electric lamp

V1 = 20 Ω × 0.25 A = 5 V

and that across the conductor

V2 = 4 Ω × 0.25 A = 1 V