14. There is an electric dipole in an ex..-阿摩線上測驗
14. There is an electric dipole in an external uniform E-field, as shown below.
Examine the following expression for the work done on the dipole:
where U(θ)=0 as θ=π/2.
(A) This expression is correct
(B) The negative sign after the second equal sign is wrong
(C) The negative sign after the last equal sign is wrong
(D) Both negative signs should be removed
(E) The dipole has a maximum potential cnergy when it is parallel to (namely,θ=0)