Question

A coil has $N$ turns and current passes through it is $I$ ampere then we obtain $L$ of self inductance. Now if current is made doubled then new self inductance be ______ H.

• A. $L/2$
• B. $2L$
• C. $L$
• D. $4L$

Hint:

Self-inductance is like the "mass" of an electrical circuit. Just as the mass of an object doesn't change when you push it harder (increase force), $L$ doesn't change when you increase current.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Self-inductance ($L$) is a geometric property of the coil. It depends on the number of turns ($N$), the area of cross-section ($A$), the length ($l$), and the permeability of the core ($\mu$).
Step 2: Formula Application:
The formula for self-inductance is $L = \frac{\mu_0 N^2 A}{l}$. Note that there is no term for current ($I$) in this formula.
Step 3: Explanation:
While the magnetic flux ($\Phi$) and the induced emf depend on the current, the constant of proportionality $L$ (defined by $\Phi = LI$) does not change when the current changes. It is an inherent characteristic of the inductor itself.
Step 4: Final Answer:
The self-inductance remains $L$.