Physics Question on electrostatic potential and capacitance

Question

If 20 J of work has to be done to move an electric charge of 4 C from a point, where potential is 10 V to another point, where potential is V volt, find the value of V.

Answer 1

Solution

If we move a charge q from point A to B, then potential
difference
$V_B - V_A = \frac{ W_{AB}}{ q}$ $\hspace20mm$ ..(i)
$V_B = V, \, V_A = 10$ volt,
$W_{ AB} = 20$ J, q = 4 C
On putting these values in E (i)
V - 10 $\frac{ 20}{ 4}$
V - 10 = 5
V = 15 volt