The material of permanent magnet is MCQ with Answer and Explanation

Question Report Error

The material of permanent magnet is

A. Steel

B. Soft iron

C. Aluminium

D. Copper

Answer: Option A

Solution (By JKExamLibrary)

Steel has high retentivity, retains magnetism, used for permanent magnets. Soft iron has low retentivity, used for electromagnet core (temporary). Alnico, ferrites also used.

This question belongs to: Science Physics

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Practice More Physics Questions

Question #1 Report Error

A 5 Ω resistor dissipates 20 W power. Current through it is

A. 2 A

B. 100 A

C. 4 A

D. 0.5 A

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Correct Answer: Option A

Explanation:
P = I² R => I = √(P/R) = √(20/5) = √4 = 2 A.

This question belongs to: Science Physics

Question #2 Report Error

A body is dropped from a height of 20 m. Its velocity on reaching ground (g=10) is

A. 10 m/s

B. 20 m/s

C. 14.14 m/s

D. 40 m/s

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Correct Answer: Option B

Explanation:
v² = 2gh = 2×10×20=400, v=20 m/s.

This question belongs to: Science Physics

Question #3 Report Error

Electric motor works on principle of:

A. Electrostatic attraction

B. Thermal expansion

C. Electromagnetic induction

D. Force on current in magnetic field

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Correct Answer: Option D

Explanation:
Motor: current-carrying conductor in magnetic field experiences Lorentz force (F = ILB), causing rotation. Generator uses reverse principle (induction). Memory tip: 'Motor: electricity ⇒ motion (force); Generator: motion ⇒ electricity (induction)'. Device principle question frequently tested in competitive electromagnetism sections.

This question belongs to: Science Physics

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