Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply.

Calculate —

(i) The total current taken from the supply,

(ii) the resistance of each heater, and

(iii) the energy supplied in kWh to the three heaters in 5 hours.

(i) Given,

Power (P) = 250 W

Voltage (V) = 100 V

Current through each heater (I) = ?

As P = VI

Substituting the values in the formula above we get,

250 = 100 x I
⇒ I = 250 / 100 = 2.5 A

Hence, current through each heater = 2.5 A

Therefore, current for three heaters =
I = 3 x 2.5 = 7.5 A

Hence, total current taken from supply = 7.5 A

(ii) Resistance for each heater (R) = ?

Since, V = IR

Substituting the values in the formula above we get,

100 = 2.5 x R
⇒ R = 100 / 2.5 = 40 Ω

Hence, resistance of each heater = 40 Ω

(iii) Energy supplied to three heater in 5 h = ?

Energy (E) = P × t

Substituting the values in the formula above, we get,

E = 250 x 5 = 1250 Wh = 1.25 kWh

Hence, Energy for three heaters = 3 × 1.25 = 3.75 kWh

Hence, energy supplied to the three heaters = 3.75 kWh