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:

$16 \times 10^{-4} T$

The correct answer is Option (1) → $16 \times 10^{-4} T$

The magnetic induction inside a solenoid is -

$B=μ_0nI$

$=(4\pi ×10^{-7})(800)×(1.6)$

$≃16 \times 10^{-4} T$