Magnitude of electric force on a proton

[Sox281212]

Homework Statement

Two protons are 2.5fm apart.
What is the magnitude of the electric force on one proton due to the other proton?

Homework Equations

Fe = K|q1||q2| / r²

The Attempt at a Solution

Fe = (9 x 10⁹)x(1.6 x 10^-19)² / (2.5 x 10^-15)²
Fe = 37 N

I got the answer but I don't understand why I am able to use e= 1.6 x 10^-19 as q1 and q2? could someone explain? thanks

 

[Orodruin]

Because both protons have this charge.

 

[rude man]

I got the answer but I don't understand why I am able to use e= 1.6 x 10^-19 as q1 and q2? could someone explain? thanks

You have two charges:
q1 = 1.6e-19C
q2 = 1.6e-19C
why wouldn't the formula F = kq1q2/r² apply here?

 

[Sox281212]

Wait, I'm confused.. isn't 1.6 x 10^-19 the charge of an electron?! Oh wait, is it because charge of electron = charge of proton if its neutral?

 

[Orodruin]

Wait, I'm confused.. isn't 1.6 x 10^-19 the charge of an electron?! Oh wait, is it because charge of electron = charge of proton if its neutral?

+1.6 x 10^-19 C is the charge of a proton. -1.6 x 10^-19 C is the charge of an electron. They are the same magnitude but of opposite sign. Also note that the unit is important, 1.6 x 10^-19 is not a charge, it is a number.

 

[Sox281212]

Thank you so much, that cleared things up :)

 

[rude man]

Wait, I'm confused.. isn't 1.6 x 10^-19 the charge of an electron?! Oh wait, is it because charge of electron = charge of proton if its neutral?

Charge of electron = -charge of proton. The thing that's neutral is the atom, comprising electrons, equal number of protons yielding the "neutrality", plus possibly neutrons which have no charge. ( The exception is ions which do have a net charge. Example: add salt to water, you get mostly sodium and chlorine ions).