Question

Figure shows two semicircular loops of radii $R_1$ and $R_2$ carrying current $I$. The magnetic field at the common centre '$O$' is

• A. \frac{\mu_0 I}{4} (\frac{1}{R_1} + \frac{1}{R_2})
• B. \frac{\mu_0 I}{4} (\frac{1}{R_1} - \frac{1}{R_2})
• C. \frac{\mu_0 I}{2\pi} (\frac{1}{R_1} + \frac{1}{R_2})
• D. \frac{\mu_0 I}{2\pi} (\frac{1}{R_1} - \frac{1}{R_2})

Hint:

The magnetic field at the center of a circular loop is $B = \frac{\mu_0 I}{2R}$. For a semicircle, it is exactly half of that, i.e., $B = \frac{\mu_0 I}{4R}$.

Answer 1

The Correct Option is A