Question

Two charges are at a distance $d$ apart. If a copper plate of thickness $\frac{d}{2}$ is kept between them, the effective force will be

• A. $\frac{F}{2}$
• B. zero
• C. $2F$
• D. $\sqrt{2F}$

Answer 1

Answer: (B)

zero

Answer 2

From Coulomb's law, electric force between two charges is directly proportional to product of charges and inversely proportional to square of distance between them. That is $F=k \frac{q_{1} q_{2}}{d^{2}}$ where, $k=\frac{1}{4 \pi \varepsilon_{0}}=$ proportionality constant. If a medium is placed between the charges, then $F'=\frac{1}{4 \pi \varepsilon_{0} K} \frac{q_{1} q_{2}}{d^{2}}$ Since, medium placed between the charges is a metallic plate, so for it $K=\infty$ Hence, $F'=0$ (zero)