JEE Main202524 Jan 2025Evening ShiftPhysicsMagnetic Effects of CurrentActual
A tightly wound long solenoid carries a current of 1.5 A . An electron is executing uniform circular motion inside the solenoid with a time period of 75 ns . The number of turns per metre in the solenoid is -. [Take mass of electron m _ e =9 10⁻³¹ ~kg , charge of electron | q _ e |=1.6 10⁻¹⁹ C , . ₀=4 10⁻⁷ ~N ~A ^2 , 1 ~ns =10⁻⁹ ~s ]
Correct answer
250
Step-by-step solution
Since time period of a revolving charge is 2 m q B Where B = magnetic field due to a solenoid = ₀ nI aligned & T = 2 ~m q ( ₀ nI ) & 75 10⁻⁹= (2 ) (9 10⁻³¹ ) 1.6 10⁻¹⁹ 4 10⁻⁷ n 1.5 & ~N =250 aligned