Question

The electric potential at a distance of 20.0 cm from a point charge is +1.0 kV (assuming V = 0 at infinity).

Is the point charge positive or negative?

At what distance is the potential +2.0 kV?

How much work is required to move an electron from the +1.0 kV position to the +2.0 kV position?

Answer 1

Here ,

the potential due to a positive charge is given as

V = K*q/d

the potential here is V = + 1 kV

as the potential is positive ,

hence, the charge is Positive .

Now, for V2 = 2 kV

d1 = 20 cm

for the same charge is

V1 * d1 = V2 * d2

1 * 20 = 2 * d2

d2 = 10 cm

the potential is +2 kV at 10 cm away
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Work required to move electron = q* (vf - vi)

Work required to move electron = -1.602 *10^-19 *(2000 - 1000)

Work required to move electron = -1.602 *10^-16 J

the Work required to move electron is -1.602 *10^-16 J