3. A student uses this apparatus to demonstrate the effect of electric charge. She pours some fine powder into a funnel.

The fine powder moves through a

length of plastic tubing and falls into a metal can.

The metal can rests on a metal

cap.

The metal cap is connected to a thin piece of metal via a metal rod.

When the powder lands in the can, the thin piece of metal moves away from the metal

rod.

a) Explain why the thin piece of metal moves away from the metal rod. (4)

b) A coulombmeter measures electric charge.

The student connects a

coulombmeter to the metal can.

When all the powder has landed in the can, the

coulombmeter shows a reading of C.

(i) Which statement is true for the metal can?

A. it gains negatively charged electrons

B. it loses negatively charged electrons

C. it gains positively charged electrons

D. it loses positively charged electrons

(ii) It takes a time of 12 s from when the powder starts landing in

the metal can until all the powder has landed in the can.

Calculate the mean charging current.

Help me !