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The following questions involve two neutral spheres. One sphere is a perfect con

ID: 1589364 • Letter: T

Question

The following questions involve two neutral spheres. One sphere is a perfect conductor and the other is a perfect insulator, but the spheres are otherwise identical. The insulating sphere is placed in a uniform external field Do charges in the sphere move? If so, describe how, and if not, explain why not. What is the magnitude and direction of the net electric field at point A? The insulating sphere is replaced with a conducting sphere as shown, in the same external field E_0 . Sketch the stable charge distribution that appears on the sphere. What is the magnitude and direction of the induced electric field at point A,9

Explanation / Answer

3a(i) No, charges do not move because it is non-conducting by its defination

3a(ii) Magnitude of electric fireld at A is Eo and its direction is rightwards i.e. in the direction of existing external field because there will not be any induced electric field as charges do not move

3b(i)Here in case of conducting the positive charges experiance force due to external field and move to the right and meanwhile negative charge will move to the left. This creates an induced electric field towards left

You can sketch the diagram keeping negative charges on left side of sphere and positive on right half of sphere. Also put an arrow right to left to show induced electric field direction

3b(ii)Magnitude of induced electric fireld at A is Eo and its direction is leftwards i.e. in the direction opposite to that of existing external field.

3b(iii)zero, because induced field and existing field cancel out each other