Question

Consider a charge of -0.3 C which is moved from a point in space at electric potential V=3 volts to one at V=1 volts. The charge begins at rest and ends at rest.

a)Along the way, does the average electric field point more or less toward the final point, or more or less away from it, on average? Justify your answer.

b) Along the way, does the average electric force point more or less toward the final point, or more or less away from it, on average?

c)Does the external force have to do positive or negative work in moving it?

d) Does the external force increase or decrease the potential energy of this charge (and the other charges that generate the potential) by this move?

Answer 1

(a) Since the filed is defined as -ve gradient of potential and directed from high potential to low potential hence at the final point, field density will be low.

(b) Same as for field hence force will be less at the final point.

(c) Since the charge is negative hence external force need to do positive work to move the charge from high potential point to low potential point

(d) As the positive work is done by the external force hence potential energy will increase of the charge.