Question

four bulbs, each of rating(100w,220v) and connected in parallel across a voltage supply of 220v are operated for five hours daily . if all the bulbs are replaced by LEDs of rating(8w,220v) , how many units of electrical energy will be saved every month(30 days )?
a) 55.2 units
b) 60 units
c) 4.8 units
d) 32 units

Answer 1

HEY!!

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▶️P= 100W = 0.1kW

▶️​t = 5× 30 = 150 hr

▶️E = P×t

▶️0.1 ×150 = 15

▶️Power for 4 bulbs = 15×4 = 60

▶️P = 8W = 0.008

▶️t = 5× 30 = 150hrs

▶️​E = 0.008 × 150

▶️1.2

▶️Power for 4 LED = 4 × 1.2 = 4.8

▶️Power saved per month = 60 - 4.8 = 55.2

▶️So option (a) is correct.