NEET-XII-Physics
qstns with ansrs year:2022
- #19A long solenoid of radius `` 1 \,mm `` has `` 100 `` turns per `` mm `` . If `` 1 \,A `` 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 ``digAnsr: CAns : `` B =\mu_{0} ni =\mu_{0} \frac{ N }{\ell} i ``
`` \therefore B =4 \pi \times 10^{-7} \times \frac{100}{10^{-3}} \times 1 ``
`` =12.56 \times 10^{-2} T ``