Question

An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.

Answer 1

The amount of heat (H) produced is given by the joule’s law of heating as H = Vlt

Where,

Current, I = 5 A

Time, t = 30s

Voltage, V = Current × Resistance

= 5 × 20

= 100 V

H = 100 × 5 × 30

= 1.5 × 10⁴ J.

Therefore, the amount of heat developed in the electric iron is 1.5 × 10⁴ J.