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Electric field:neutral sphere 
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#1
Jan2708, 05:29 PM

P: 4

It is known that a neutral metal ball will have 0 electric field inside the sphere, will there be a non zero electric field inside the neutral metal ball if this neutral ball is placed near a charge? I know that it will induce charges of the opposite kind ont he outside, what about the inside.
thanks 


#2
Jan2708, 07:16 PM

P: 65

Based on Gauss's law, there should not be a charge enclosed, because all of the charge is on the surface. So at some region r<R (r is a radius less than the Radius of the sphere) of the sphere would have zero charge. But the surface of the sphere would have a charge.
This applies for a hollow sphere. 


#3
Jan2708, 09:16 PM

Sci Advisor
P: 1,594

If the sphere is a conductor, then the electric field will be zero everywhere inside the sphere. Think about it: in a conductor, charges are free to move. So if there is a net electric field, then the charges will move...and they will continue moving until there is no net electric field. That is, the charges will arrange themselves in a way that precisely cancels the field inside the sphere.
There will, however, be an induced charge distribution on the surface of the sphere, and that means that the electric field outside the sphere will get complicated. 


#4
Jan2708, 09:45 PM

Sci Advisor
PF Gold
P: 1,776

Electric field:neutral sphere



#5
Jan2908, 06:05 PM

P: 516

Does anyone have the mathematical proof that the Efield is 0?
Ie that in a hollow sphere made of insulating material, if the charge is evenly distributed on the surface (so the charges cannot move) then the Efield is zero? 


#6
Feb108, 09:34 AM

P: 9

I would say that for a conductor (hollow or solid) the field is zero *IF* the charge on the surface (whether induced or not) is static  if there was a field then the charges would not be static (as was mentioned before). So the assumption is that you waited to look for the field (a millionth of a second or so) until the charges reached their equiilbrium positions and if they are staying put then the field must be zero. Note that the electric field inside a currentcarrying conductor is not zero  that's what makes the charges move!



#7
Feb108, 03:42 PM

Sci Advisor
P: 1,594

I meant, complicated relative to the OP's (assumed) understanding of electrostatics. 


#8
Mar3108, 03:07 PM

P: 23

can anyone prove it mathematically using probably gauss law or something?



#9
Apr308, 06:33 AM

P: 19

Gauss law is only really tractable analytically for charged cases about three cases (spherical symmetry, infinite line of charge, infinite plane of charge). Nevertheless, it's always true. if there's no charge inside your region, the surface integral over your gaussian surface is zero.



#10
Apr308, 07:26 AM

P: 516




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