Question

An electric bulb is rated at 200V - 100W. What is its resistance? Five such bulbs burn for 4 hours. What is the electric energy consumed?

Answer 1

power = V x I 
100 = 200 x I 
I = 1/2 amps 
R = E/I = 100 / 0.5 = 200 ohms 

4 x 100 watts = 400 watts 

400 watts x 4 hours = 1600 watt-hours (energy) or 1.6 kW-hours 

1.6 kW-hours x 50 paise / kW-hours = 80 paise 
(assuming "unit" means kW-hour)

hope it may helps.....

Answer 2

$\huge\fbox\orange{\underline{Question:–}}$

An electric bulb is rated at 200w-100w what is the resistance of 5 such bulbs burn for 4 hours. What is the electrical energy consumed. Calculate the cost if the rate is 50 paise per unit.

$\huge\fbox\orange{\underline{Answer:–}}$

Using, P = $\large{V²}{R}$

we get R = $\large{V²}{P}$

= $\large{(200)²}{100}$

= 400

Energy consumed = P x t

= 100 x 4

= 400 Wh

= 0.4 kWh

Cost at the rate of 50 paise per unit

= Rs (0.50 x 0.4)

= Rs 2

HOPE IT HELPS

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