Q. A long solenoid of radius 1 mm has 100 turns per mm. If 1A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is :
A) $6.28 \times 10^{-4}$ T
B) $6.28 \times 10^{-2}$ T
C) $12.56 \times 10^{-2}$ T
D) $12.56 \times 10^{-4}$ T
Explanation
[Solution] n = $10^5$ turns/m; $B = \mu_0 n I = 4\pi \times 10^{-7} \times 10^5 \times 1 = 12.56 \times 10^{-2}$ T. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.