If you have two charges q1 and q2, you can get the force between them F by multiplying them with the coulomb constant K (approximately 9 × 10^9) and then dividing that by the distance between them squared r^2.

q1 and q2 cannot be negative. Sometimes you'll not be given a charge, and instead the problem will tell you that you have a proton or electron, both of them have the same charge (1.6 × 10^-19 C), but electrons have a negative charge.

[–] Kolrami@lemmy.world 5 points 1 year ago (1 children)

q1 and q2 can be negative. The force is the same as if they were positive because -1 x -1 = 1

[–] Limitless_screaming@kbin.social 1 points 1 year ago (1 children)

In this case yes, but if q1 was -20μC, q2 was 30μC, and r was 0.5m, then using -20μC as it is would make F equal to -21.6N which is just 21.6N of attraction force between the two charges.

[–] Pelicanen@sopuli.xyz 3 points 1 year ago (1 children)

If they are oppositely charged particles, I would expect that there is a force of attraction acting on them, yes.

[–] Limitless_screaming@kbin.social 0 points 1 year ago (1 children)

I am not saying that's wrong, just that there's 21.6N of attraction force between the two charges not -21.6N.

[–] Pelicanen@sopuli.xyz 1 points 1 year ago (1 children)

But those are the same thing.

[–] Bene7rddso@feddit.de 2 points 1 year ago (1 children)

No, if the force is negative it acts in the opposite direction

[–] Pelicanen@sopuli.xyz 1 points 1 year ago

Yes, and a force acting in the opposite direction of the distance is an attractive force.