UNCHARGED METAL SPHERE NEAR A CHARGED RODCHARGE DISTRIBUTION

UNCHARGED METAL SPHERE NEAR A CHARGED ROD-CHARGE DISTRIBUTION A student observes a demonstration involving an interaction between a neutral metallic sphere suspended from a string and a negatively charged insulating rod. The student makes the following statement: \"As the negatively charged rod nears the sphere, it causes the electrons in the sphere to move away from the rod. The side of the sphere nearest to the rod becomes positively charged while the other side becomes negatively charged. So the sphere will be attracted toward the rod. If they touch the Sphere will saving back since they will both become neutral.\" What, if anything, is wrong with this statement? If something is wrong, explain the error and how to correct it. If the statement is valid, explain why.

Solution

1.As the negatively charged rod nears the sphere ,it causes the electrons in the sphere to move away from the rod,This is a correct statement.

2.The side of the sphere nearest to the rod becomes positively charged while the other side becomes negatively charged ..So the sphere will be attraceted towards the rod .This is correct statement

3.If they touch the sphere will swing back since they will both become neutral.

This is an incorrect statement since the rod it is an insulator. Only a small amount of charge on the surface of the rod will transfer to the metal spherewhere contact is made , which would be having negative net charge.