Electromagnets 23. To hold fire doors open, an electromagnet is switched on, generating a magnetic field If a solenoid is 2.00 cm long, has 400 turns, carries a current of 1.90 A and its core is air, calculate the magnetic flux density inside the solenoid, in tesla

0.0478 T

Explanation:

L = 2 cm = 0.02 m, N = 400, i = 1.9 A

The magnetic field intensity due to a current carrying solenoid is given by

B = / mu _{0}ni

Where, n be the number of turns per unit length

n = N / L = 400 / 0.02 = 20,000

B = 4/pi / times 10^{-7}/times 20000/times 1.9

B = 0.0478 T