Question

at constant potential difference the resistance of any circuit is halved the value of heat produced will be

Answer 1

At constant potential difference, the resistance of any electric circuit is halved, the value of heat produced will be $\bf{doubled}$ .

explanation : we know, heat produced in circuit =$\frac{V^2}{R}t$

[ note : when potential difference is constant , you should choose the formula, H = $\frac{V^2}{R}t$ , but question says that heat produced at constant current, then you should use formula, H = i²Rt ]

now, here you can see Heat is inversely proportional to resistance. so, if resistance of any electric circuit is halved , then the value of heat produced will be doubled.

Answer 2

Given :

Potential difference is constant

Resistance is halved

Heat produced =?

Formula :

H= I²Rt

H= V²/R² XRxt [ since V=IR]

H= V²t/R

So H is inversely proportional to R

If R is halved then

H=V²t/(R/2)

H= 2(V²t/R)

so heat produced  will be doubled.

So if resistance decreases , heat produced will increase