Answer & explanation
Correct answer: option 2
$\text{magnetic field due to straight part is zero}$
$ \text{Magnetic field due to circular parts are }B = B_1 -B_2 = \frac{\mu_0 3I/4}{4R} - \frac{\mu_0 I/4}{4R} = \frac{\mu_0I}{8R}$
Correct answer: option 2
$\text{magnetic field due to straight part is zero}$
$ \text{Magnetic field due to circular parts are }B = B_1 -B_2 = \frac{\mu_0 3I/4}{4R} - \frac{\mu_0 I/4}{4R} = \frac{\mu_0I}{8R}$