- Home
- Standard 12
- Physics
2. Electric Potential and Capacitance
medium
A parallel plate capacitor has plate area $A$ and separation $d$. It is charged to a potential difference $V_o$. The charging battery is disconnected and the plates are pulled apart to three times the initial separation. The work required to separate the plates is
A
$\frac{{3{\varepsilon _0}AV_0^2}}{d}$
B
$\frac{{{\varepsilon _0}AV_0^2}}{{2d}}$
C
$\frac{{{\varepsilon _0}AV_0^2}}{{3d}}$
D
$\frac{{{\varepsilon _0}AV_0^2}}{d}$
Solution
(d) Work done $W = {U_f} – {U_i}$
${U_i} = \frac{1}{2}C{V_0}^2{\rm{\, and \,}}{{\rm{U}}_{\rm{f}}} = \frac{1}{2}\frac{{(C)}}{3}.{(3{V_0})^2}$$ = 3 \times \frac{1}{2}C{V_0}^2$
So $W = \frac{{{\varepsilon _0}A{V_0}^2}}{d}$
Standard 12
Physics
