Question

What is power?
(a) 41 W
(b) 110 W
(d) 1100 W
1. An electrical heater is used for 5 hours on a
220 V supply and takes a current of 5 amperes.​

Answer 1

Answer:

Power =P=VI⟹1000=250I⟹I=

250

1000

=4A

∴(i) Electric current flowing through heater=I=4A

∴(ii) Resistance of heated wire R=

I

V

=

4

250

=62.5Ω

∴(iii) Thermal energy produced per minute by heater=E

T

=P×1min=1000×60sec=60000J

∴(iv) Electrical energy spent in kilowatt-hour by heater in 2 hours=

1000

P

KW×2hour=2KW-hour