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Electromagnetic Induction — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Induction1 Mark
Question
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b ), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and Rare true but R is NOT the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion (A): Induced e.m.f. depends on number of turns and area of the coil.
Reason (R): Induced e.m.f. increases with increase in number of turns of coil.
✓

Answer

  1. Both A and Rare true but R is NOT the correct explanation of A.

Explanation: 

According to Faraday's law, the induced e.m.f.

$\varepsilon=\frac{-\text{d(N}\phi)}{\text{dt}}=-\frac{\text{d(NBA)}}{\text{dt}}=-\text{NA}\frac{\text{dB}}{\text{dt}}.$

Thus the induced e.m.f. depends on the rate of change of magnetic flux, number of tums of coil and area of the coil. If any of these factor increases (or decreases) then induced e.m.f. also increases (or decreases).

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