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ICSE Class 8 Physics Question 4 of 18

Household Electricity — Question 4

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Question

Question 4

In a premise 5 bulbs each of 100 W, 2 fans each of 60 W, 2 A.Cs each of 1.5 kW are used for 5 h per day. Find:

(a) total power consumed per day,

(b) total power consumed in 30 days,

(c) total electrical energy consumed in 30 days,

(d) the cost of electricity at the rate of Rs 6.25 per unit.

Answer

(a) Power consumed by 5 bulbs = 5 x 100 = 500 W
Power consumed by 2 fans = 2 x 60 = 120 W
Power consumed by 2 A.Cs = 2 x 1.5 = 3 kW or 3 x 1000 = 3000 W
Total power consumed per day = 500 + 120 + 3000 = 3620 W

Total power consumed per day = 3620 W.

(b) Power consumed for 30 days = 30 x 3620 = 108600 W or 108.6 kW

Power consumed for 30 days = 108.6 kW.

(c) Power consumed in 30 days = 108.6 kW
time = 5 h

Electrical energy consumed in 30 days = Power x time
= 108.6 x 5
= 543 kWh

Electrical energy consumed in 30 days = 543 kWh.

(d) Cost of 1 unit = Rs 6.25
Cost of 543 units = 6.25 x 543 = Rs 3393.75

Cost of electricity = Rs 3393.75.