Question

Assertion :The magnetic field produced by a current carrying solenoid Is independent of its length and cross-sectional area. Reason: The magnetic field inside the solenoid is uniform.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Magnetic field inside the solenoid at point P is given by,
$B=\frac{{\mu }_0}{4\pi }\left(2\pi ni\right)[\sin \alpha +\sin \beta ]$
Where n=no. of turns per unit length $=N/l$
Thus it is clear that magnetic field is independent of length and cross sectional area.
Also the magnetic field with in the solenoid is uniform and parallel to the axis of the solenoid.