Question

A bulb is rated 200V-40W. What is its resistance? 5 such bulbs are lighted for 5 hours. Calculate the electricity energy consumed. Find the cost if the rate is Rs. 5.10 per kWh.

Answer 1

$HeyThere!!$

V = 200 V, P = 40 W

P = V × I

I = P / V
= 40 / 200
= 1 / 5 A

R = V / I
= 200 / ( 1/5 )
= 200 × 5
= 1000 ohm

Total power = 40W × 5
= 200 Wh

Time = 5 hours

Electrical energy = 200W × 5 hours
= 1000 Wh
= 1 kWh

Cost of 1 kWh = Rs. 5.10

Answer 2

Dear Friend,

● Answer -

Energy consumed = 1 kWh

Cost of energy = 5.1 ₹

◆ Explanation -

# Given -

V = 200 V

P = 40 W

N = 5 bulbs

t = 5 hrs

cost = 5.10 ₹/kWh

# Solution -

Energy consumed by each bulb -

E = P × t

E = 40 × 5

E = 200 Wh

Total energy consumed by all bulbs -

ET = E × N

ET = 200 × 5

ET = 1000 Wh

ET = 1 kWh

Hence, cost of 1 kWh = 5.10 ₹ .

Thanks for asking..