Question

The potential difference applied across a given resistor is altered so that the heat produced per second is increased by a factor of 99 what factor potential difference changes

Answer 1

Let original Potential difference applied is V and original Heat Produced is H. 

Then, H = V^2t\over R…………(1)

New potential difference is V' and Heat Produced after change is H'.

Then, 

H' = {V'^2t\over R} …………(2)

According To question,

H' = 9H

=> {V'^2t\over R} =9\times {V^2t\over R} 

=> V'2 = 9V2

=> V' = 3V

So potential difference is increased by a factor 3.