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    Question

    Two identical circular current-carrying loops, placed

    coaxially, carry the same current i in the same direction . As the loops are brought closer to each other, what will happen to the current in each loop?
    A The current in both loops will decrease Correct Answer Incorrect Answer
    B The current in both loops will increase Correct Answer Incorrect Answer
    C The current in each loop will remain unchanged Correct Answer Incorrect Answer
    D The current will increase in one and decrease in the other Correct Answer Incorrect Answer

    Solution

    Given:

    • Two identical circular loops
    • Carry same current i in same direction
    • Placed coaxially (on the same axis)
    Now, when two loops carrying current in the same direction are brought closer , each loop's magnetic field supports the other loop’s magnetic field.
    Thus, the mutual inductance MMM between the loops increases . Now, by Lenz’s law :
    • Any change that tends to increase magnetic flux opposes the original current.
    • So, when mutual inductance MMM increases, to oppose the increased flux, an induced emf is created which tries to decrease the original current.
    Thus the current in both loops will decrease.

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