One of the two small circular coils, (none of them having any self- inductance) is suspended with a \(V-\) shaped copper wire, with plane horizontal. The other coil is placed just below the first one with plane horizontal. Both the coils are connected in series with a \(dc\) supply. The coils are found to attract each other with a force. Which one of the following statements is incorrect ?

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Answer & Solution

Correct Answer

(D) Force is proportional to \(d^{-2}\)

Step-by-step Solution

Detailed explanation

As the force between the two coils is attractive hence currents in the coil must be in the same direction and the force,

\(F \propto \frac{{{I_1}{I_2}}}{{2\pi d}}\)

where \(I_1\) and \(I_2\) are the currents flowing through the coils.

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