Which Rod Rotation Induces EMF in a Magnetic Field?

[Terocamo]

Homework Statement

Which of the following action would cause and e.m.f. induced in the conductor?
1. The rod is rotating about an axis parallel to the B field through one end of the rod.
2. The rod is rotating about an axis perpendicular to the B field through one end of the rod.
3. The rod is rotating about an axis through the mid point perpendicular to the B field.

The Attempt at a Solution

I know 1 will have a voltage build up and 3 will not but i have trouble understanding 2, the answer said there is emf in rod 2.

 

[anathema]

Hi there,

I can provide some insight on the electromagnetic induction process and how it applies to the given scenarios.

To understand why there is an induced emf in scenario 2, it is important to first understand the concept of magnetic flux. Magnetic flux is a measure of the amount of magnetic field passing through a given area. When there is a change in magnetic flux, an emf is induced in a conductor.

In scenario 2, the rod is rotating about an axis perpendicular to the magnetic field. This means that the area of the rod that is perpendicular to the magnetic field is changing as it rotates. This change in area results in a change in magnetic flux, which in turn induces an emf in the conductor.

In contrast, in scenario 1, the area of the rod that is perpendicular to the magnetic field remains constant as it rotates. Therefore, there is no change in magnetic flux and no induced emf.

In scenario 3, the axis of rotation is through the midpoint of the rod, which means that the area of the rod perpendicular to the magnetic field is changing, but the change is symmetrical on both sides of the midpoint. This results in an equal and opposite induced emf on either side, canceling each other out and resulting in no net induced emf.

I hope this helps to clarify why there is an induced emf in scenario 2 and not in scenarios 1 and 3. Keep up the good work in your studies!