When a coil is placed in a constant external magnetic field directed perpendicular to the plane of the coil, which of the following actions does not induce an emf in the coil?

moving the coil through the field without changing its orientation with respect to the field
removing the coil from the field
rotating the coil
collapsing the coil
changing the strength of the magnetic field

moving the coil through the field without changing its orientation with respect to the field

Explanation:

An emf can only be induced in the coil by whatever action that causes a change in the flux through the coil.

The following descriptions all change the flux through the coil and induce

an emf:

removing the coil from the field

rotating the coil

collapsing the coil

changing the strength of the magnetic field

However, moving the coil through the constant field without changing its orientation with respect to the field will not cause a change of flux. Hence the chosen answer.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.