A Level Physics-Electric Fields help

Watch
cruduxcruo9
Badges: 8
Rep:
?
#1
Report Thread starter 8 months ago
#1
For (b) of this question a method in the mark scheme states V = Ex (for a point charge) where x is distance. Can anyone explain this equation?
Last edited by cruduxcruo9; 8 months ago
0
reply
swinroy
Badges: 12
Rep:
?
#2
Report 8 months ago
#2
(Original post by cruduxcruo9)
For (b) of this question a method in the mark scheme states V = Ex (for a point charge) where x is distance. Can anyone explain this equation?
I can understand your dilemma. This is the grey area where a full Maths analysis is needed. BUT as a shortcut ...(*x is a distance) because
Potential Difference = (Force / Charge) x Distance
But this formula only works when the Force on the Charge is Constant and the Electric Field is Constant (NOT TRUE for point charges)
Clearly, thus is not the case so we have to revert to calculus and say that
THE AREA Under the Force - Distance graph is the Energy or Work Done.
But you have a graph of Electric Field v Distance so you need to make a factor adjustment of this. Force = Electric Field x Charge
0
reply
Eimmanuel
Badges: 13
Rep:
?
#3
Report 8 months ago
#3
(Original post by cruduxcruo9)
For (b) of this question a method in the mark scheme states V = Ex (for a point charge) where x is distance. Can anyone explain this equation?

The equation or expression V = Ex is actually


 V = \dfrac{Q}{4\pi \epsilon_0 x }

in the disguise.

If a point charge Q is responsible for the electric field, then the magnitude of electric field strength of the point charge Q is


 E = \dfrac{Q}{4\pi \epsilon_0 x^2 }

and the electric potential due to the point charge Q is


 V = Ex = \dfrac{Q}{4\pi \epsilon_0 x^2 } \times  x = \dfrac{Q}{4\pi \epsilon_0 x }
1
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Current uni students - are you thinking of dropping out of university?

Yes, I'm seriously considering dropping out (153)
14.56%
I'm not sure (46)
4.38%
No, I'm going to stick it out for now (312)
29.69%
I have already dropped out (27)
2.57%
I'm not a current university student (513)
48.81%

Watched Threads

View All
Latest
My Feed