Electrical Dipoles Flashcards
1
Q
What is an electrical dipole?
A
A pair of charges +q and -q separated by a fixed distance d
2
Q
What is the electric dipole moment?
A
p=qd
Where d points from negative to positive
3
Q
What is the torque?
A
τ=r x F
τ=FL
4
Q
How is the direction of τ found?
A
Right hand rule with thumb in direction of τ
Fingers curl in direction torque would rotate
5
Q
What is the torque about the centre of the dipole?
A
τ=p x E
With p the dipole moment and e the electric field
6
Q
What is the work done for rotation?
A
dW=τdϕ
dW=-pEsinϕdϕ
7
Q
What is the work done for linear motion?
A
W=F.d
8
Q
What is the potential energy of an electric dipole?
A
u(ϕ)=- p.E
u(ϕ)=-pEcosϕ
