Solved: PHYSICS Question for NEET

NEET PHYSICSEasy

An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has a magnitude:

\frac{\mu_0 ne}{2\pi r}

Zero

\frac{n^2e}{r}

\frac{\mu_0 ne}{2r}

Equivalent Current ( $I$ ): An electron (charge $e$ ) revolving in a circular orbit constitutes an electric current. By definition, current is the rate of flow of charge ( $I = q/t$ ) . If the electron makes $n$ rotations per second (frequency $f = n$ ), the time period for one revolution is $T = 1/n$ . Thus, the equivalent current is: $I = \frac{e}{T} = e \cdot n$
Magnetic Field at Center ( $B$ ): The magnitude of the magnetic field at the center of a circular current-carrying loop of radius $r$ is derived from the Biot-Savart law and is given by: $B = \frac{\mu_0 I}{2r}$ .
Calculation: Substituting the expression for equivalent current ( $I = ne$ ) into the magnetic field formula: $B = \frac{\mu_0 (ne)}{2r}$

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