Question

Two metallic spheres of radii $1cm$ and $3cm$ are given charges of $-1\times {10}^{-2}C$ and $5\times {10}^{-2}C$, respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is-

• A. $3\times {10}^{-2}C$
• B. $4\times {10}^{-2}C$
• C. $1\times {10}^{-2}C$
• D. $2\times {10}^{-2}C$

Answer 1

Answer: (A)

$3\times {10}^{-2}C$

$Q_{total}=5\times {10}^{-2}C-1\times {10}^{-2}C=4\times {10}^{-2}C$
We know that,
Charge distribution $\propto$ radius
$\therefore$ $Q_{small}:Q_{big}=1:3$
$Q_{big}=\frac{3}{4}\times 4\times {10}^{-2}=3\times {10}^{-2}C$