The magnetic flux density at a point on the axis of a long solenoid having 1000 turns/m when it is carrying a current of 3.4 A is nearly,

$4.4 \times 10^{-3} T$

The correct answer is Option (4) → $4.4 \times 10^{-3} T$

The magnetic flux density $(\vec B)$ at a point on the axis of a long solenoid is given by the -

$B=μ_0nI$

where,

$μ_0$ = Permeability of space = $4π×10^{-7}$

$n$ = Number of turns

$I$ = Current through solenoid

$B=(4π×10^{-7})×1000×3.4$

$≃4.4 \times 10^{-3} T$