Question

an electric device rated 1000w, 220v is connected to the mains. calculate
(i) its resistance
(ii) energy consumed by it in 5 hrs
(iii) cost of energy consumed if each unit costs rs.3.00

Answer 1

Resistance=48.4 ohm

Energy consumed=5 Kwh

Cost=RS.15

Answer 2

Hello dear,

● Answer -
R = 40 ohm
W = 5 kWh
Cost = ₹ 15

● Explaination-
# Given-
P = 1000 W
V = 200 V
t = 5 hrs
Cost = ₹ 3 /unit

# Solution-
Power of the electric device is calculated by-
P = V^2 / R
R = V^2 / P
R = 200^2 / 1000
R = 40 ohm

Energy consumed in 5 hrs is -
W = Pt
W = 1000 × 5
W = 5000 Wh
W = 5 kWh

Cost of energy is given by-
Cost = 3 × 5
Cost = ₹ 15

Hope it helps...