I'm revising for my exam and got stuck in the following questions. Please help.(adsbygoogle = window.adsbygoogle || []).push({});

1) An isolated spherical conductor of radius r is charged to a potential V. The total electrical energy stored is _______.

This is an MC question and the answer is V^{2}(2*pi*ε_{o}*r)

I only know energy stored = Qq/(4*pi*ε_{o}*r) and V=Q/(4*pi*ε_{o}*r)

2)A positively-charged metal sphere A of radius a is joined by a conducting wire to an uncharged metal sphere B of radius b placed far away from the first sphere. THe ratio of the surface charged density on sphere A to that on sphere B is ______.

The answer is b/a.

Well, I know surface area of A :surface area of B = a^2:b^2. How can I get the answer b/a ?

Thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Electric field

**Physics Forums | Science Articles, Homework Help, Discussion**