Electric field conductor problem

In summary, for the first problem, you need to use the formula for the energy stored in an isolated conductor, which is Q^2/(4*pi*epsilon*r). Using this formula and the given information, you can calculate the total electrical energy stored. The answer is not V^2(2*pi*epsilon*r) as previously thought, but rather V^2(4*pi*epsilon*r). This means the given answer was incorrect.For the second problem, you need to use the ratio of surface areas between the two spheres, which is a^2:b^2. This means the ratio of surface charged density on sphere A to that on sphere B is b/a.
  • #1
KLscilevothma
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I'm revising for my exam and got stuck in the following questions. Please help.

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 V2(2*pi*εo*r)
I only know energy stored = Qq/(4*pi*εo*r) and V=Q/(4*pi*εo*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.
 
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  • #2
In the first problem you have an incorrect formula: this is an "isolated" conductor so you do NOT have two charges, q and Q.
Since you have only one charge, Q, you need to use
energy stored = Q2/(4*pi*epsilon*r).

You also know V=Q/(4*pi*epsilon*r) so Q= V/(4*pi*epsilon*r) and Q2= V2/(4*pi*epsilon*r)2. Substitute that into the first equation and then simplify.
 
  • #3
That means the answer isn't V^2(2*pi*eplison*r) but V^2(4*pi*eplison*r). I'm pretty sure I was given a wrong answer.
Thanks.
 

1. What is an electric field conductor problem?

An electric field conductor problem refers to a situation where there is an electric field present in a conductor or between two conductors. This can occur when there is a difference in electrical potential between the conductors, causing an electric field to be established.

2. What causes an electric field conductor problem?

An electric field conductor problem can be caused by a number of factors, such as a difference in electrical potential between conductors, the presence of charged particles, or the movement of electrons within the conductor.

3. How is an electric field conductor problem measured?

The strength of an electric field conductor problem can be measured by using a device called an electric field meter. This device measures the electric field in volts per meter (V/m) and can also indicate the direction of the field.

4. What are the potential hazards of an electric field conductor problem?

An electric field conductor problem can pose a danger to individuals who come in contact with it, as it can cause electric shock or burns. It can also damage electronic equipment or disrupt communication signals.

5. How can an electric field conductor problem be resolved?

An electric field conductor problem can be resolved by using proper insulating materials to prevent contact with the conductor, or by grounding the conductor to dissipate the electric field. In some cases, the problem can be resolved by adjusting the electrical potential difference between conductors.

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