A cylindrical bar magnet is rotated about its axis (Figure). A wire is connect from the axis and is made to touch the cylindrical surface through a contact. Then

Options

A. a direct current flows in the ammeter A
B. no current flows in the ammeter A
C. an alternating sinusoidal current flows through ammeter A with a time period `T=(2pi)/(omega)`
D. a time varying non-sinusoidal current flows through the ammeter A

Answer

B

Explanation

What cylindrical bar magnet is rotated about its axis, no change in flux linked with the circuit takes place, consequently no emf induces and hence no current flwos through the ammeter A.