A dipole of moment p$=3\mathrm{.}8$times $10\mathrm{³}\mathrm{⁰}$ Cm is placed in a uniform field of

modulus E$=7$times $10\mathrm{⁴}$ N$/$C$.$

a$)$ What is the external work necessary to rotate the dipole by $60$^o from

of an initial position parallel to the electric field?

b$)$ When the dipole makes an angle of $60$^o with the field, what is the modulus of the moment of force exerted on it by this field?