(a) According to the Joule's law of heating, heat produced in a resistor is directly proportional to the :
(i) square of current (I) for a given resistance.
(ii) resistance (R) for a given current.
(iii) the time ( t ) for which the current. flows through the resistor.
Mathematical form of Joule's law of heating is :
H=I2Rt
(b) Given, charge (q)=96000C
Time (t)=2‌hrs=120‌min=7200 s
Potential difference (V)=40 volt
We know that,
Heat (H)=V It, where I is current...(i)
Also,
I=q∕t, where q is charge and t is time in seconds.....(ii)
∴ By putting I=q∕t in eqn. (1) we get,
H‌=(V×q∕t)×t=Vqt∕t=Vq
⇒H‌=40×96000‌ joule ‌
⇒H‌=3840000‌ joule ‌