Find the net force that the southern hemisphere of a uniformly charged solid sphere exerts on the northern hemisphere. Express your answer in terms of the radius R and the total charge Q.

Respuesta :

Answer:

Explanation:

The final net force will be in the Z- direction. Let's find out the z component of the force on the differential volume of charge is:

df = dqEcosθz

[tex]E = \frac{1}{4\pi epsilon} \frac{Qr}{R^{3} }[/tex]

dq = ρdV =  [tex]\frac{3Q}{4\pi R^{3} }[/tex][tex]r^{2}[/tex]dr.sinθdθdΦ

integrate it over half ball,

[tex]F_{z} = \int\limits^._V {df_{x}dV} =\frac{1}{4\pi epsilon } \frac{Q}{R^{3} } \frac{3Q}{4\pi R^{3} }\int\limits^R_0 {\int\limits^\frac{\pi }{2} _{0} {\int\limits^\frac{\pi }{2} _0 {r^{3} } \, dr } \, } \,[/tex].sinθcosθdθdΦ.( these are part of the integral, i was unable to write it in equation format).

    = [tex]\frac{3Q^{2} }{32\pi epsilonR^{2} } \int\limits^\frac{\pi }{2} _b {} \,[/tex]  sinθcosθdθ

   

   = [tex]\frac{3Q^{2} }{64\pi epsilon R^{2} }[/tex]

[tex]F = \frac{3Q^{2} }{64\pi epsilon R^{2} } z[/tex]