The figure shows a steady electric current passing through a wire with a narrow region.What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?
A) The drift velocity decreases from A to B and increases from B to C.
B) The drift velocity increases all the time.
C) The drift velocity remains constant.
D) The drift velocity decreases all the time.
E) The drift velocity increases from A to B and decreases from B to C.

Question

The figure shows a steady electric current passing through a wire with a narrow region.What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C? 
A) The drift velocity decreases from A to B and increases from B to C. 
B) The drift velocity increases all the time. 
C) The drift velocity remains constant. 
D) The drift velocity decreases all the time. 
E) The drift velocity increases from A to B and decreases from B to C.

Quizplus · Accepted Answer

In region A, the wire is wider, so there is more space for the moving charges to spread out, which reduces their resistance to motion and increases their drift velocity. In region B, the wire is narrow, so there is less space for the moving charges to spread out, which increases their resistance to motion and decreases their drift velocity. In region C, the wire widens again, allowing the moving charges to spread out and reduce their resistance to motion, which increases their drift velocity. Therefore, the drift velocity increases from A to B and then decreases from B to C, which is only found in option E.

The Figure Shows a Steady Electric Current Passing Through a Wire