Question

Assertion :In coin-operated vending machine, eddy currents are used to detect counterfeit coins, or slugs. Reason: The coin rolls past a stationary magnet, and eddy currents slow its speed. The strength of the eddy currents, and thus the retardation, depends on the conductivity of the coin's metal.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Eddy current a localized electric current induced in a conductor by a varying magnetic field. Its strength depends upon the conductivity of the material. When the coin passes through the magnetic field, then due to the relative change happening in the magnetic field the eddy currents are induced in the coin. This coin then suffers retardation because of the consequence of Lenz's law, which says that the coin will oppose any relative change in the magnetic flux. Counterfeit coins are detected by the vending machine when they show any abnormality in this behavior. Or when they do not have specific value of retardation. Also the value of current depends upon the conductivity of material.