Register to reply

Effect of radius changes on electric fields and potential difference?

by mirandab17
Tags: electric field, electric potential
Share this thread:
mirandab17
#1
Jan31-12, 01:21 AM
P: 40


Hello!

Okay so I understand that electric potential:

V = kQ/r

...must be influenced by the radius doubling because it would make the potential energy half of what it originally was because of the proportionality law, v is proportional to 1/r.

With electric fields though, how can there possibly be no change? The formula is

E = kQ/r^2

...meaning if should be influenced as well?

The answer is c, btw.
Phys.Org News Partner Science news on Phys.org
Hoverbike drone project for air transport takes off
Earlier Stone Age artifacts found in Northern Cape of South Africa
Study reveals new characteristics of complex oxide surfaces
Simon Bridge
#2
Jan31-12, 05:39 AM
Homework
Sci Advisor
HW Helper
Thanks ∞
Simon Bridge's Avatar
P: 12,434
So do the math - calculate the field before and after the change in position.
Note: E is a vector.
mirandab17
#3
Jan31-12, 08:46 AM
P: 40
Oh! Right!

Since E is a vector, and the distance and charges on both sides are equal, then they always simply cancel out to zero. Whereas with electric potential, a scalar quantity, it is not affected by direction, merely magnitude, in which case both are positive, so the radius change will definitely affect it.

Thanks bud!

Simon Bridge
#4
Jan31-12, 09:14 AM
Homework
Sci Advisor
HW Helper
Thanks ∞
Simon Bridge's Avatar
P: 12,434
Effect of radius changes on electric fields and potential difference?

No worries - that "Oh! Right!" feeling is what I was going for :)


Register to reply

Related Discussions
Electric Fields and Potential Difference. Combining Formulae Introductory Physics Homework 1
Electric Fields and Potential Difference General Physics 2
Electric Potential Difference Question (Parallel plates, higher potential) Introductory Physics Homework 1
Electric fields, distance, and potential difference Introductory Physics Homework 4
Electric Potential Energy and Electric Potential Difference Introductory Physics Homework 2