Three heaters each rated 250 W, 100 V are connected in parallel to a 1

1.	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.
Answer» Given, Power, p = 250 w Voltage, v = 100 v (i) current through each heater, I = ? As p = VI ⇒ I = P/V = 250/100 = 2.5 A ∴ Current taken for the three heaters = 3 × 2.5 = 7.5 A (ii) resistance for each heater, R = V/I = 100/2.5 = 40Ω (iii) Time for which energy is supplied, t = 5h As, Energy, E = p × t E = 250 × 5 = 1250 wh Or E = 1.25 kwh Energy for three heaters = 3 × 1.25 = 3. 75 kwh

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.

Answer»

Given,

Power, p = 250 w

Voltage, v = 100 v

(i) current through each heater, I = ?

As p = VI

⇒ I = P/V

= 250/100 = 2.5 A

∴ Current taken for the three heaters = 3 × 2.5 = 7.5 A

(ii) resistance for each heater, R = V/I

= 100/2.5 = 40Ω

(iii) Time for which energy is supplied, t = 5h

As, Energy, E = p × t

E = 250 × 5 = 1250 wh

E = 1.25 kwh

Energy for three heaters = 3 × 1.25 = 3. 75 kwh