Ampere's Circuital Law: Practice Problem & Solution

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Ampere's Circuital Law. Understanding the underlying formula is key to arriving at the correct answer below:

The magnetic field inside a long solenoid is given by $B = \mu_0 n I$. Given $n = 100\text{ turns/mm} = 10^5\text{ turns/m}$ and $I = 1\text{ A}$, substituting the values yields $B = (4\pi \times 10^{-7}) \times 10^5 \times 1 = 12.56 \times 10^{-2}\text{ T}$.