The phenomenon of electromagnetic induction is the basis for the working of:
A. Transformer
B. Electric motor
C. Both (b) and (c)
D. Generator
Answer: Option C
Solution (By JKSSB Mock Tests)
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.
Explanation:
For spherical mirrors, R = 2f. So R = 2 × 15 = 30 cm. Sign convention: for concave mirror, f and R are negative by Cartesian convention, but magnitude 30 cm. So 30 cm is correct.
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