Question

A long solenoid has 200 turns/cm and carries a current of 2.5 amp the magnetic field at its centre is

Answer 1

Q -> A long solenoid has 200 turns/cm and carries a current of 2.5 amp the magnetic field at its centre is....

solution : magnetic field at the centre of long solenoid is given by, $B=\mu_0ni$

where B is magnetic field, $\mu_0$ is permeability of vaccum/air i.e., $\mu_0$ = 4π × 10^-7 T/Am

n is number of turns per meter and i is current through solenoid.

given, n = 200 turns/cm = 200 × 100 turns/m = 20000 turns/m

i = 2.5 amp

now, B = 4π × 10^-7 × 20000 × 2.5

= 4π × 10^-7 × 2 × 10⁴ × 2.5

= 20π × 10^-3 T

= 2π × 10^-2 T

= 6.28 × 10^-2 T [ as π = 3.14 ]

hence, magnetic field at centre of solenoid is 6.28 × 10^-2 T.