Question

A 6.0 µC point charge is 0.030 m from another point charge and experiences a repulsive force of 180 N. What is the magnitude of the other charge? (µC = 1.0 × 10^-6 C)

-6.0 µC
-3.0 µC
+3.0 µC
+6.0 µC

Answer 1

you could use the formula \[\large F=q1 q2 / 4\pi (\epsilon 0) r ^{2}\]

so substitute everything you have and you will can get the charge

Answer 2

then for the sign of the charge remember that opposites attract, and like repel

so if they have opposite signs, the force will be attractive
if they have the same signs, the force between them will be repulsive

Answer 3

i substituted everything in and this is what it looks like:
180N = (6.0µC) q^2 /4pi (ϵ0) 0.030m^2

Answer 4

ok everything is right except that you have q^2, it is supposed to be just q2
I think you just wrote it accidentally

Answer 5

yeah that was an accident haha sorry

Answer 6

and like before do not forget to change the charge into C not microC

Answer 7

okay! what is the value for ϵ0 btw?

Answer 8

epsilon 0 equals 8.85 x 10^-12 C^2/ N times m^2 and it is a constant by the way

Answer 9

the answer that i got rounds to 3

Answer 10

so it would be -3.0 µC ?

Answer 11

well as I explained earlier, opposite charges attract but you have a repulsive force so they must have the same sign for the charges

Answer 12

never mind yeah i meant +3.0 µC sorry

Answer 13

i was thinking about your comment thats why said the opposite one haha

Answer 14

no problem! I am glad you get this though

Answer 15

thank you so much for your help and for taking your time to help me understand it! :)

Answer 16

no problem I am glad that you are willing to understand