Question

If the current flowing in a coil is reduced to half of its original value, the relation between the new energy (E₂) and the original energy (E₁) stored in the coil will be

(A) E₂ = E₁

(B) E₂ = 2E₁

(C) E₂ = $\frac{1}{2}$E₁

(D) E₂ = $\frac{1}{4}$E₁

Answer 1

The Correct option is  D)  E₂ = $\frac{1}{4}$E₁  

Explaination  

 Current is become half of the given value. 

$E=\frac{1}{2}L{i}^2$ 

i.e. 

$\frac{E_2}{E_1}=(\frac{i_2}{i_1}{)}^2=(\frac{1}{2}{)}^2$         __{current halfs i₂=1/2 i_1}

_{$E_2=\frac{1}{4}{E}_1$}