Electric motor works on principle of: MCQ with Answer and Explanation

Electric motor works on principle of:
A. Electrostatic attraction
B. Force on current in magnetic field
C. Thermal expansion
D. Electromagnetic induction
Answer: Option B
Solution (By JKSSB Mock Tests)
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.

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Practice More Physics Questions

Question #1
The gravitational force between two masses is F. If the distance is tripled, force becomes
A. 9F
B. F/9
C. F/3
D. 3F

Correct Answer: Option B


Explanation:
F ∝ 1/r², so if r→3r, F→F/9.

This question belongs to: Science Physics
Question #2
According to Pascal's law, pressure applied to an enclosed fluid is transmitted
A. Only in downward direction
B. In direction of flow only
C. Undiminished in all directions
D. With loss of magnitude

Correct Answer: Option C


Explanation:
Pascal's law: pressure applied to a confined incompressible fluid is transmitted equally and undiminished in all directions. Hydraulic lift, hydraulic brakes work on this principle. P = F₁/A₁ = F₂/A₂.

This question belongs to: Science Physics
Question #3
The range of audible frequency is
A. 20 kHz - 200 kHz
B. 20 Hz - 20000 Hz
C. 1 Hz - 100 Hz
D. 0 - 20 Hz

Correct Answer: Option B


Explanation:
20 Hz to 20 kHz.

This question belongs to: Science Physics