Question

If $\vec{r}=x\hat{i}+y\hat{j}+z\hat{k}$ and $r=\sqrt{x^2+y^2+z^2}$, then grad $(\frac{1}{r})$ is equal to :

• A. $-\frac{\vec{r}}{r^3}$
• B. $-\frac{\vec{r}}{r^2}$
• C. $\frac{\vec{r}}{r^3}$
• D. $\frac{\vec{r}}{r}$

Answer 1

Answer: (A)

$-\frac{\vec{r}}{r^3}$

Answer 2

The correct option is(A):$-\frac{\vec{r}}{r^3}$.