Electric potential at a point distant $0.5 \,m$ from a spherical conductor of radius $0.2 \,m$ charged to $+1 \,nC$ is

$A$ particle '$A$' has charge '$+q$' and a particle '$B$' has charge '$+4q$'. Each has the same mass '$m$'. When they are allowed to fall from rest through the same potential difference '$V$',the ratio of their speeds will be (particle $A$ to particle $B$):

Consider two concentric conducting spheres of radii $R$ and $2R$ respectively. The inner sphere is given a charge $+Q$. The outer sphere is grounded. The potential at $r = \frac{3R}{2}$ is

$A$ spherical shell of radius $10 \,cm$ is carrying a charge $q$. If the electric potential at distances $5 \,cm$, $10 \,cm$, and $15 \,cm$ from the centre of the spherical shell is $V_{1}$, $V_{2}$, and $V_{3}$ respectively, then:

Figures $(a)$ and $(b)$ show the field lines of a positive and negative point charge respectively.
$(a)$ Give the signs of the potential difference $V_{P}-V_{Q}$ and $V_{B}-V_{A}$.
$(b)$ Give the sign of the potential energy difference of a small negative charge between the points $Q$ and $P$,and $A$ and $B$.
$(c)$ Give the sign of the work done by the field in moving a small positive charge from $Q$ to $P$.
$(d)$ Give the sign of the work done by the external agency in moving a small negative charge from $B$ to $A$.
$(e)$ Does the kinetic energy of a small negative charge increase or decrease in going from $B$ to $A$?

$A$ hollow metallic sphere of radius $R$ is given a charge $Q$. Then the potential at the centre is