The electric potential at a point in an electric field is 0.5 V.  How much work has to be done to bring a charge of 3 C from infinity to that point?

Electric potential = 0.5 V
Charge = 3 C
Work done =?

We know that electric potential at a point is defined as the work done in bringing unit charge from infinity to the point.

$\mathrm{Electric} \mathrm{potential} \left(\mathrm{V}\right) = \frac{\mathrm{Work} \mathrm{done}\left(\mathrm{W}\right)}{\mathrm{charge}\left(\mathrm{Q}\right)}$

Thus, the amount of work W, done in moving the charge is:

$\mathrm{W} = \mathrm{V} \times \mathrm{Q}$
$\mathrm{W} = 0.5 \mathrm{V} \times 3 \mathrm{C}$
$\mathrm{W} = 1.5 \mathrm{J}$

Therefore, the amount of work W, done in moving the charge is 1.5 J.