91影视

The term work done may be defined as the amount of force acting upon a body which causes displacement.

The given quantities are

$$\begin{gathered} V_i=+30脳{10}^{-3}V \\ {V}_f=-70脳{10}^{-3}V \\ \frac{C_m}{A}=1.0脳{10}^{-2}{\text{F/m}}^{\text{2}} \\ F={10}^5\text{C/mol} \end{gathered}$$

The change in the potential energy of the capacitor is:

$螖U=\frac{1}{2}C\left[V_f^2-V_i^2\right]$

and for the total capacitance of the spherical egg need to multiply the capacitance of unit area by the surface area of the egg so,

$C=\frac{C_m}{A}脳4蟺r^2$

Put all the given values,

$$\begin{gathered} C=1.0脳{10}^{-2}脳4蟺(100脳{10}^{-6}{)}^2 \\ C=1.26脳{10}^{-9}\text{F} \end{gathered}$$

Hence, the whole capacitance of the spherical egg is $C=1.26脳{10}^{-9}F$.

The change in the potential energy of the capacitor is :

$螖U=\frac{1}{2}C\left[V_f^2-V_i^2\right]$

Put all the given values,

$$\begin{gathered} 螖U=\frac{1}{2}脳1.26脳{10}^{-9}\left[{\left(-70脳{10}^{-3}\right)}^2-{\left(+30脳{10}^{-3}\right)}^2\right] \\ 螖U=2.51脳{10}^{-12}\text{J} \\ 螖U=2.5\text{pJ} \end{gathered}$$

Hence, the minimum amount of work done is$3pJ$ . The correct option is (d).