Question

A conducting rod $PQ$ of length $1m$ is moving with a uniform speed $2m{s}^{-1}$ in a uniform magnetic field of $4T$ which is directed into the paper. A capacitor of capacity $10\mu F$ is connected as shown in the figure. Then the charges on the plates of the capacitor are

• A. $q_A=+80\mu C;q_B=-80\mu C$
• B. $q_A=-80\mu C;q_B=+80\mu C$
• C. $q_A=+1.25\mu C;q_B=-1.25\mu C$
• D. $q_A=-1.25\mu C;q_B=+1.25\mu C$

Answer 1

Answer: (A)

Charge on each plate should be
where, $q=CV$
$V=vBl$
$\Rightarrow q=C(vBl)$
$=10\times 10^{-6}\times 2\times 4\times 1$
$q=80\mu C$
So, charges on plates are $\pm 80\mu C$.