The phenomenon of electromagnetic induction is the basis for the working of: MCQ with Answer and Explanation

The phenomenon of electromagnetic induction is the basis for the working of:
A. Transformer
B. Generator
C. Electric motor
D. Both (b) and (c)
Answer: Option D
Solution (By JKExamLibrary)
Electromagnetic induction (changing magnetic flux induces EMF) is the principle behind generators (mechanical energy to electrical) and transformers (AC voltage conversion). Electric motors work on the reverse principle: force on current-carrying conductor in magnetic field. Memory aid: 'Induction applications: generators, transformers, induction cooktops; motors use motor effect'. This application question tests electromagnetism fundamentals, frequently examined in competitive exams. Always distinguish induction (generator/transformer) from motor effect (motor); competitive exams often combine both in device-based questions.

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Practice More Physics Questions

Question #1
Which SI prefix represents 10⁻⁶?
A. milli
B. micro
C. nano
D. pico

Correct Answer: Option B


Explanation:
Micro (μ) denotes 10⁻⁶ in SI system. Nano = 10⁻⁹, pico = 10⁻¹², milli = 10⁻³. Standard prefixes: kilo(10³), milli(10⁻³), micro(10⁻⁶), nano(10⁻⁹). Memory aid: 'Micro = millionth; μm = micrometer = 10⁻⁶ m'. Frequently tested for unit conversion proficiency in competitive exams.

This question belongs to: Science Physics
Question #2
A lactometer is used to check
A. Purity of milk
B. Humidity
C. Blood pressure
D. Purity of water

Correct Answer: Option A


Explanation:
Measures specific gravity of milk, indicates adulteration.

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Question #3
A car travels from point A to B with speed 40 km/h and returns from B to A with speed 60 km/h. The average speed for the entire journey is:
A. 45 km/h
B. 50 km/h
C. 52 km/h
D. 48 km/h

Correct Answer: Option D


Explanation:
Average speed = Total distance / Total time. Let distance AB = d km. Time for AB = d/40 h, time for BA = d/60 h. Total distance = 2d km. Total time = d/40 + d/60 = d(3+2)/120 = 5d/120 = d/24 h. Average speed = 2d / (d/24) = 48 km/h. Note: Average speed is not arithmetic mean of speeds (which would be 50 km/h) because time intervals differ. This harmonic mean concept is crucial for motion problems. Exam tip: For equal distances, average speed = 2v₁v₂/(v₁+v₂). Frequently tested in competitive exams.

This question belongs to: Science Physics