A very long solenoid has 800 turns per unit length. A current of 1.6 A flows through it. Then the magnetic induction in the middle of the solenoid on its axis is approximately:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 16\times10^{-4}\,\mathrm{T} \)
Inside a long solenoid, away from its ends, the field is uniform and given by \( B = \mu_0 nI \), where n is the number of turns per unit length (taken per metre).
\( B = 4\pi\times10^{-7}\times800\times1.6\,\mathrm{T} \)
\( B = 1.61\times10^{-3}\,\mathrm{T} \approx 16\times10^{-4}\,\mathrm{T} \)