Question

A charged particle of +9.0 nC is .052 m from the origin on the negative y-axis. Another charged particle of -4.5 nC is .079 m from the origin on the positive x-axis.

a) What is the net electric force on an electron placed at the origin? (include direction)

b) What is the net electric force on a proton placed at the origin? (include direction)

c) Which particle has a higher potential energy?

Answer 1

a)

Force due to +x axis charge

F1 = k e q1 / r1^2

F1 = 9*10^9* 1.6*10^-19* 4.5*10^-9 / 0.079^2

F1 = 1.25 *10^-15 N

Force due to charge on y axis

F2 = k e q2 / r2^2

F2 = 9*10^9* 1.6*10^-19* 9*10^-9 / 0.052^2

F2 = 4.793*10^-15 N

Net force on electron

F^2 = F1^2 + F2^2

F = 4.953*10^-15 N

Direction  

phi = 180 + arctan ( F2/ F1)

phi = 255.38 ccw from +x axis

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b)

Asthe charge is same so force acts on it due to other two charges would be same.

F = 4.953*10^-15 N

Direction,

Phi = arctan ( F2 /F1)

Phi = 75.38 ccw from +x axis

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C)

Since proton has positive charge, so proton has higher potential energy.

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