(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The prototypical electric dipole is made of two equal and opposite charges of magnitude q separated by a constant distance d (for example, the charges can be placed at opposite ends of a length d rod).

The dipole is placed in a uniform, external electric field Er = E0 yˆ . The positive charge is at coordinates (x, y, z) = (+d/2 sinθ, +d/2 cosθ, 0) and the negative charge is at coordinates (x, y, z) = (–d/2 sinθ, –d/2 cosθ, 0).

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a) What is the electric force on each charge? What is the net force on the dipole?

b) What is the net torque on the dipole? At what angle(s) will the net torque be zero?

c) The dipole is initially oriented perpendicular to the electric field (θ = 90°). How much work does it take to rotate the dipole so that it is parallel to the electric field (θ = 0°)? Anti- parallel (θ = 180°)? (Hint: Take the voltage to be zero at the origin and find what potential difference each charge moves through.)

d) Now consider the dipole oriented along the x-axis and centered on the origin. Sketch this configuration, and draw some field lines (using the convention that a charge q gets 8 field lines) and at least 5 equipotential lines.

2. Relevant equations

F = kQQ/r^2

p= qd

t = pE

3. The attempt at a solution

F on q+ = (9x10^9)Q^2 / d^2 sin^2 θ+ d^2 cos^2 θ

F on q- = (9x10^9)Q^2 / d^2 sin^2 θ+ d^2 cos^2 θ

F net = 0

τ = Qd^2sin^2 θ + d^2cos^2 θ + E0y^

I dont know if I am doing this right. Any help would be greatly appreciated!

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Electric dipole in uniform electric field

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