Question

A long solenoid is made by closely winding a wire
of radius 0.5 mm over a cylindrical non-magnetic
frame so that successive turns nearly touch each
other. What will be the magnetic field at the centre
of the solenoid if a current of 5 A flows through it?
​

Answer 1

Answer:

The turns of wire on the solenoid are shown in figure.

Number of turns in 1mm =1

n=1000turns/m

∴B=μ0ni

=4π×10−7×103×5

=2π×10−3T.

Answer 2

Answer:

your answer is in attachment