NEET2015Physics-Magnetism
NEET 2015 Physics Magnetic Field in Solenoids MCQ Question
Type: MCQ-conceptual-Medium-Class 12
The magnetic field inside a long solenoid is given by B = μ₀ni, where n is the number of turns per unit length and i is the current. If the solenoid is bent into a circle, the magnetic field at the center of the circle is:
A
11/5 μ₀ni
B
3μ₀ni
C
16/5 μ₀ni
D
4μ₀ni
Correct Answer
Option C
Detailed Explanation
When a solenoid is bent into a circle, it forms a toroid. The magnetic field inside a toroid is given by B = (μ₀ni)/2πr, where r is the radius of the toroid. For a complete circle, the effective length is 2πr, leading to the factor of 16/5.
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