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Alternating Current — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current1 Mark
Question
For 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 R are 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: The core of transformer is made laminated in order to increase the eddy currents.
Reason: The sensitivity of transformer increases with increase in the eddy currents.
✓

Answer

  1. A is false and R is also false.

Explanation:

Eddy current is produced in the iron core due to induced e.m.f. Since resistance of the iron core is quite small, the magnitude of eddy currents is quite large. As a result, large amount of heat is produced. To avoid it, a laminated core is used in a transformer. ln laminated core iron stripes are quite thin and each strip possesses very large resistance, the magnitude of eddy currents produced is quite small and hence only a small amount of heat is produced.

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