Electric Field Question?
I would like to learn how a specific answer (in part B) was derived at.
The problem I'm working on is as follows:
A uranium nucleus has 92 protons. Assume the nucleus to be a point-like charge Q = 92e and ignore interact with other electrons.
A) Determine the magnitude of the E field at a distance of 6.4 x 10^-13 m from the nucleus (about the radius of the innermost electron orbit around the nucleus).
I understand how to complete this part and the relevant equations.
k = 9.0 x 10^9 Nm^2/C^2
E = kq/r^2
e = 1.6 x 10^-19 C
I set up my formula as follows:
(9.0 x 10^9 Nm^2/C^2)(92)(1.6 x 10^-19 C) / (6.4 x 10^-13 m)^2
= 3.2 x 10^17 N/C
B) What is the magnitude of the force exerted on an electron by this E field?
*This is where I'm unsure what to do*
The answer is 5.2 x 10^-2 N, but I'm unsure of how to arrive there based on the information that I have.
- Steve4PhysicsLv 73 months agoFavorite Answer
The unrounded answer from part a) is 3.2344x10^17 N/C. It's best to use this unrounded value in part b).
The force on charge q in field E is simply F = qE. We can ignore the electron charge's minus sign as we are only asked for the magnitude of F.
F = qE
. .= (1.6x10^-19 C) x (3.2344x10^7 N/C)
. .= 0.05175N
Rounded to 2 sig. figs. we can write this as 5.2x10^-2 N.