Two positive point charges (at ) and (at ) are fixed on a straight line

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Two positive point charges

q_1 = +4\,\mu\text{C}

(at

x = 0

) and

q_2 = +6\,\mu\text{C}

(at

x = 0.30\,\text{m}

) are fixed on a straight line. A third charge

q_3

is to be placed at

x = 0.90\,\text{m}

so that the net electrostatic force on

q_2

is zero. What should be the value of

q_3

? (a)

+8\,\mu\text{C}

(b)

-16\,\mu\text{C}

(c)

+16\,\mu\text{C}

(d)

+36\,\mu\text{C}