Question

Two charges of magnitude $4\mu C$ and $-9\mu C$ are $0.5m$ apart. The electric intensity is zero at a distance x m from A and y m from B. x and y are respectively:

• A. $0.5m,1.0m$
• B. $1.0m,1.5m$
• C. $2.0m,1.5m$
• D. $1.5m,2.0m$

Answer 1

The correct option is B $1.0m,1.5m$

Here, $y=x+0.5$

Electric field at point P due to charge at A $=E_1=\frac{k{q}_1}{x^2}$

Electric field at point P due to charge at B $=E_2=\frac{k{q}_2}{(x+0.5{)}^2}$

Here, $q_1=4\mu C$

$q_2=-9\mu C$

$E_1+E_2=0$

$⟹\frac{4}{x^2}=\frac{9}{(x+0.5{)}^2}$

$⟹x=1$

$⟹y=1.5$