$A$ charge $+Q$ is placed at the centre of a circular path of radius $r$. The work done to bring a charge $+q$ from one end of the diameter to the other end of the circular path in the electric field produced by charge $+Q$ is $.......$

The equation of an equipotential line in an electric field is $y = 2x$. The electric field strength vector at $(1, 2)$ may be:

$A$ conducting sphere of radius $r$ has a charge. Then

This question has Statement-$1$ and Statement-$2$. Of the four choices given after the Statements,choose the one that best describes the two Statements.
Statement-$1$: No work is required to be done to move a test charge between any two points on an equipotential surface.
Statement-$2$: Electric lines of force at the equipotential surfaces are mutually perpendicular to each other.

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Work done by an electric field on moving a positive charge on an equipotential surface is always zero.
Reason $(R)$: Electric lines of force are always perpendicular to equipotential surfaces.
In the light of the above statements,choose the most appropriate answer from the options given below:

In moving from $A$ to $B$ along an electric field line,the electric field does $6.4 \times 10^{-19} \, J$ of work on an electron. If $\phi_1$ and $\phi_2$ are equipotential surfaces,then the potential difference $(V_C - V_A)$ is.....$V$.