A straight wire of length is oriented east-west and is in a magnetic field B pointing north.The wire is moving downward at a constant speed v.Which end of the rod is positively charged?
A)neither
B)the east end
C)the west end
D)both ends

Question

A straight wire of length  is oriented east-west and is in a magnetic field B pointing north.The wire is moving downward at a constant speed v.Which end of the rod is positively charged?
A)neither 
B)the east end 
C)the west end 
D)both ends

Quizplus · Accepted Answer

The direction of induced current in a moving conductor is perpendicular to both the direction of motion and the magnetic field. In this case, the induced current will flow upwards on the east side and downwards on the west side. By the right-hand rule, this creates a magnetic field pointing towards the south on the east side and towards the north on the west side.

Since the wire is moving downwards, the electrons are moving upwards on the east side and downwards on the west side. Therefore, the east end of the wire is negatively charged and the west end is positively charged.

Therefore, the answer is B, the west end of the wire is positively charged.

A Straight Wire of Length Is Oriented East-West and Is