a van der graaf generator is used to build up charges on the outside of a sphere. a belt is charged with electrons by rubbing against a rough pulley. these electrons are then transferred to a metal sphere and spread out even on its outer surface. when neutral objects are brought near the sphere, they are attracted to the sphere before they touch each other.
what evidence from the prompt can you give that charges can be moved by induction

"When neutral objects are brought near the sphere, they are attracted to the sphere before they touch each other."

Explanation:

Charging by induction is said to occur when an uncharged object is brought near a charged body and it gets attracted towards it without even the two bodies touching.

The charged body polarizes the uncharged body. The charges shift to either sides and that causes the force of attraction between the two.

Suppose a negatively charged body is brought close to an uncharged body. The electrons of the body repel from the side near to the charged body and shift to the other end leaving behind positive ions.

The last line of the given paragraph indicates that charges can be moved by induction.

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)