Question

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.

Answer 1

R = 8 ohm
I = 15A
t = 2 hrs
rate of heat developed = (I^2Rt)/t
=I^2R
= (15)^2 × 8
=225 × 8
= 1800W

Answer 2

As per the given details, we can take the resistance of electrical heater as R and current as I.

The given time duration t is 2 hours.  

The rate of heat is calculated below.  

R = 8 ohm

I = 15A

t = 2 hrs

The rate of heat developed = (I^2Rt)/t

=I^2R

= (15)^2 × 8

= 1800W