Question

The armature of a DC motor is rotating in the clockwise direction as shown. What is the direction of the magnetic field for the given motor?

• A. Left to right
• B. Right to left
• C. Vertically upwards
• D. Vertically downwards

Answer 1

The correct option is B Right to left


When the loop/armature is rotating in clockwise direction means the left arm of the loop is moving vertically upwards.

by Applying Fleming's Left hand Rule

1. Here, the left arm of the loop is moving vertically upwards. So, the thumb of your left hand will point upwards.
2. The direction of current will be away from you, so your middle finger will point away from you.
3. The forefinger now gives us the direction of the magnetic field, which is from right to left.

• You could verify this in the right arm of the loop. The right arm is moving downwards, the current is directed towards you. So the forefinger again points towards the left, Hence the magnetic field is from right to left.