Please answer Q3 fast

When an electric charge Q moves against a potential difference V,the amount of work done is given by

W=Q x V-----(I)

We also know that

I=Q/t

So Q=I x t---(i)

And from Ohm's law

V=IR--------(ii)

Putting Q=I x t and V=IR in (I),We get

W=I x t x Ix R

Work done

So Joule’s law of heating states that when a current ‘I' passes through a conductor of resistance ‘R’ for time ‘t’ then the heat developed in the conductor is equal to the product of the square of the current, the resistance and time.

now 
H= V²t/R
V= (HR/t)^1/2
V=( 220 X 8/1)^1/2
V= 42 V

Thanks and regards.