Question

an electric bulbs rated at 200v-100w .what is its resistance? five such bulbs burn for four hours . what is the electrical energy ?

Answer 1

here p = 100 w
v = 200v
therefore we know

》p = v^2 / r
》r = v^2 / p
= (200 × 200) / 100 = 400 ohms


if five such bulbs rated for four hours then energy of the system is given by

》E = (5p) / (4 × 60 × 60)
= 500 / 14400 = 0.0347222 joules


hope it helps

Answer 2

P=100
V=200
R=200*200/100
R=400ohm

P of one bulb =100W
P of 5 bulb =500W
time=4hours
electrical energy =0.5kw*4
=2KWH