Question

The strength of the magnetic field inside a long current carrying a straight solenoid is

• A. more at the ends than at the center
• B. minimum in the middle
• C. same at all points
• D. found to increase from one end to the other

Answer 1

The correct option is C

same at all points

Solenoid

1. It is a tightly wound helical loop from an insulated wire, such that its length is very large as compared to its diameter.
2. The magnetic field inside a solenoid is

$B={\mu }_{o}nI$

n = number of turns per unit length

I = Applied current

3. Inside a solenoid, the value of the magnetic field doesn't depend on the position inside the solenoid.

4. This implies that the magnetic field inside a long solenoid is constant.

Hence, the correct option is (C) same at all points.