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,
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → \( 4.3\times10^{-3}\,\mathrm{T} \)
Inside a long solenoid (at a point on its axis well away from the ends) the field is uniform, \( B = \mu_0 nI \), where n is the number of turns per unit length.
\( B = 4\pi\times10^{-7}\,\mathrm{T\,m\,A^{-1}}\times1000\,\mathrm{m^{-1}}\times3.4\,\mathrm{A} \)
\( B \approx 4.3\times10^{-3}\,\mathrm{T} \)