A point charge is placed at the origin

PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A point charge

q_1=+8\,\mu\text{C}

is placed at the origin. Another charge

q_2

is placed on the positive

y

-axis at the point

(0,0.12\,\text{m})

. The magnitude of the force experienced by

q_2

due to

q_1

is measured to be

4\,\text{N}

and the force is directed along the positive

y

-axis. (a) Write an expression for the magnitude of the force between the two charges in terms of

q_2

. (b) Using the given data, calculate the numerical value (magnitude and sign) of

q_2

. (c) Comment briefly on whether the sign obtained for

q_2

is consistent with the stated direction of the force.