Q.
A long solenoid of 50cm length having 100turns carries a current of 2.5A. The magnetic field at the centre of the solenoid is : (μo​=4π×10−7TmA−1)
Magnetic field at centre of solenoid =μ0​nI n=LN​ =50×10−2100​ =200 tums/m I=2.5A
On putting the values, B=4π×10−7×200×2.5 =6.28×10−4T