Question

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

Answer 1

R = square of V/P

Therefore, R = 200*200/40

= 1000 ohm

E = V*V*t/R

Therefore, E = 200*200*5*3600/1000

( t = 5*3600 sec)

E = 72000J

= 720 kJ

For 5 bulb = 720*5= 3600J

kWh= 3600000/3600

= 1000kWh

Cost = 1000*5.1 = 5100Rs

This is the solution of this question...

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