Electric field strength Flashcards
1
Q
What is the electric field strength?
A
- E
- E at a point in the field is defined as the force per unit charge on a positive test charge placed at that point
2
Q
Between oppostely charged flat conductors that are parallel to eachother
what are the field lines
A
- parallel to eachother
- at right angles to the plates
- from a positive plate to the negative plate
3
Q
Why is the field between the parallel oppositely charged plates unifomr?
A
- E has the same magnitude and direction everywhere between the plates
- E = V /d
- V= pd
- d = distance
4
Q
Derive the equation V=Ed.
W=Fd
F=QE
A
- V is W per unit Q
- V = W / Q
- if charge moved from +ve to -ve then wrok done by the field on Q is biven by W = Fd = QEd
- therefore V = W / Q = QEd / Q = Ed
5
Q
What determines the strength of the electric field?
A
- charge density
- charge conc on the surface
- therefore E is propotional to Q / A
6
Q
What is the constant of propotionallity for E ∝ Q / A
A
- ε0
- permittivity of free space
- Q / A = Eε0
- represents that charge per unit area on a surface in an electric field strength of one volt per metre between the plates
- dont need to know
7
Q
Is electric field strength scalar or ector?
A
- vector
- pointing in direction a positive charge would move
8
Q
State reason why the acceleration of particles in an electric field are different fro each particle?
A
- mass and charge are not constant and vary
- a = Eq / m
- E is constant, but q and m vary
- therefore, q / m unlikel;y to be the same
