Question

When a capacitor of value 200 uF charged to 200V is discharge separately through resistance of 2 ohms and 8 ohms, then heat produced in joule will respectively be:

Answer 1

$\text{Step 1: Potential energy stored in capacitor}$

$U=\frac{1}{2}C{V}^2$

$=\frac{1}{2}\times (200\times {10}^{-6}F)\times (200V{)}^2$

$=4$ Joules

$\text{Step 2: Heat produced}$

On discharging, all the energy stored in the capacitor will be dissipated as heat through the connected resistor.

Hence, Heat produced $H=4J$

Here heat produced is independent of value of resistance connected.

So, in both cases the heat produced will be $4$ J.

$\text{Note:}$ The value of resistance will effect only the time of discharging, not the total heat. As time constant during discharging $\tau =RC$. Higher the value of resistance, capacitor will take more time to discharge.