A bullet is fired into a fixed target looses one third of its velocity after travelling $$4 \mathrm{~cm}$$. It penetrates further $$\mathrm{D} \times 10^{-3} \mathrm{~m}$$ before coming to rest. The value of $$\mathrm{D}$$ is :

Three voltmeters, all having different internal resistances are joined as shown in figure. When some potential difference is applied across $$A$$ and $$B$$, their readings are $$V_1, V_2$$ and $$V_3$$. Choose the correct option.

The equation of state of a real gas is given by $$\left(\mathrm{P}+\frac{\mathrm{a}}{\mathrm{V}^2}\right)(\mathrm{V}-\mathrm{b})=\mathrm{RT}$$, where $$\mathrm{P}, \mathrm{V}$$ and $$\mathrm{T}$$ are pressure, volume and temperature respectively and $$\mathrm{R}$$ is the universal gas constant. The dimensions of $$\frac{\mathrm{a}}{\mathrm{b}^2}$$ is similar to that of :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Work done by electric field on moving a positive charge on an equipotential surface is always zero.

Reason (R) : Electric lines of forces are always perpendicular to equipotential surfaces.

In the light of the above statements, choose the most appropriate answer from the options given below :