Question

A conducting rod of Length $L=0.1$m is moving with a uniform speed $v=0.2$ m/s on conducting rails in a magnetic field $B=0.5$T as shown. On one side, the end of the rails is connected to a capacitor of capacitance $C=20\mu F$. Then the charges on the capacitor plates are.

• A. $q_A=0=q_B$
• B. $q_A=+20\mu C$ and $q_B=-20\mu C$
• C. $q_A=+0.2\mu C$ and $q_B=-0.2\mu C$
• D. $q_A=-0.2\mu C$ and $q_B=+0.2\mu C$

Answer 1

The correct option is C $q_A=+0.2\mu C$ and $q_B=-0.2\mu C$

$L=0.1m$ , $v=0.2m{s}^{-1}$ ,$B=0.5T$ ,$C=20\mu F$

$V=BvL$

=$0.5\times 0.2\times 0.1$=$0.01$

$q=cv=20\mu F\times 0.01=0.2\mu C$

$q_A=+0.2\mu C$

$q_B=-0.2\mu C$