Question Detail

PHY 102 Electromagnetic Induction Objective Question

Question

What happens to the back emf in a motor as the rotational speed increases?
Options
A It decreases
B It increases
Correct Answer
C It remains constant
D It becomes zero
Correct Answer

Option B is the correct answer.

Detailed Explanation

Back emf is proportional to the rate at which the armature cuts magnetic flux lines (ε_b ∝ ω). As rotational speed increases, back emf increases.

Hint

Faster rotation → larger back emf.

Question Info