Q. Charge Q is given a displacement $ \Large \vec{r}= a\hat{i}+ b\hat{j} $ in an electric field $ \large \vec{E}= E_1\hat{i} + E_2\hat{j} $ . The work done is

(a) Q(E_{1}a + E_{2}b)

(b)$ \large Q\sqrt {(E_1a )^2+ (E_2 b)^2} $

(c) $ \large Q(E_1+E_2)\sqrt {(a )^2+ (b)^2} $

(d) $\large Q\sqrt{(E_1^2+E_2^2)} \sqrt {(a )^2+ (b)^2} $

Ans:(a)