Question
Assertion : A laminated core is used in transformers to increase eddy currents.
Reason : The efficiency of a transformer increases with increase in eddy currents.
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Answer
Large eddy currents are produced in nonlaminated iron core of the transformer by the induced $emf$, as the resistance of bulk iron core is very small. By using thin iron sheets as core the resistance is increased. Laminating the core substantially reduces the eddy currents. Eddy current heats up the core of the transformer. More the eddy currents greater is the loss of energy and the efficiency goes down.
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