Why is E-field 0 outside of this sphere?

[flyingpig]

Homework Statement

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2. Solutions

For b) - iv

They say the E-field is 0 for r > c

Why?

Also for part c), they say the answer should be the integral from r = a to r = b.

My question is, why isn't it from r = a to r = c (c is the surface of the other sphere)?

What does "grounding" the sphere actually tell you?

 

[SSJVegetto]

Since the outer sphere is a conducting sphere the charges will be attracted to one side of the sphere due to the electric field caused by the charge at the center. So the field when the charge is positive is directed radially outward, this causes the elctrons to move to the inner part of the sphere while leaving the outer part positively charged and thus a field is generated inside the material which cancels the field of the charge.

For you final question the field in the outer sphere is zero and therefore the potential difference is not altered within the conducting shell since it has no magnetic field inside.

If you have any questions please ask!

 

[SammyS]

Grounding the spherical shell means that its electric potential is made to be zero. Therefore, you know that the electric field outside the shell is zero. Also, the net charge on the outer surface of the shell is zero.