Question

A heater takes a current of 7 A from a 230 V source for 12 h. Calculate the energy consumed (in kWh).
1. 2.76 kWh
2. 1.61 kWh
3. 38.64 kWh
4. 19.32 kWh

Answer 1

Correct Answer - Option 4 : 19.32 kWh

CONCEPT:

Heating effect of electric current:
When a current is flowing in a circuit having resistance there is a heat dissipation due to the resistance. This is called the heating effect of electric current.

The Heat dissipated (H) is given by:

H = I2Rt .... (1)

Where I = the current flowing in the circuit, R = the resistance of the circuit, and t = the time taken

According to Ohms law,

V = IR .... (2)

From equation (1) and (2)

\(H=VIt\)

EXPLANATION:

Given that:

I = 7 A

V = 230 V

t = 12 h

Hence, Energy consumed or heat dissipate is given as,

H = 230 × 7 × 12 = 19320 Wh = 19.32 kWh