NEET Self Induction MCQs & PYQs

Q: A coil resistance 20 Ω and inductance 5 H is connected with a 100 V battery. Energy stored in the coil will be :

$$I = \frac{V}{R} = \frac{100}{20} = 5 \text{ A}$$ $$U = \frac{1}{2} L I^2 = \frac{1}{2} \times 5 \times 5^2 = 62.5 \text{ J}$$ Energy stored = 62.5 J

Practice NEET Self Induction Questions

Question 1:

easy

The self inductance of a toroid is :

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Question 2:

moderate

A varying current in a coil changes from 10 amp to zero in 0.5 sec. If average EMF is induced in
the coil is 220 volts, the self inductance of coil is :

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Question 3:

moderate

How much length of a very thin wire is required to obtain a solenoid of length l0 and inductance L.

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Question 4:

difficult

What is the mutual inductance of a two-loop system as shown with centre separation l ?

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Question 5:

easy

A coil resistance 20 Ω and inductance 5 H is connected with a 100 V battery. Energy stored in the coil will be :

I = \frac{V}{R} = \frac{100}{20} = 5 \text{ A}

U = \frac{1}{2} L I^2 = \frac{1}{2} \times 5 \times 5^2 = 62.5 \text{ J}

Energy stored = 62.5 J

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Question 6:

easy

A current of $2\text{ A}$ is increasing at a rate of $4\text{ A/s}$ through a coil of inductance $2\text{ H}$. The energy stored in the inductor per unit time in given instant is:

Formula for rate of change of energy in an inductor is $\frac{dU}{dt} = LI\frac{dI}{dt}$. Given $L = 2\text{ H}$, $I = 2\text{ A}$, and $\frac{dI}{dt} = 4\text{ A/s}$, we get $\frac{dU}{dt} = 2 \times 2 \times 4 = 16\text{ J/s}$.

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Question 7:

easy

A coil of $\text{Cu}$ wire (radius $r$, self inductance $L$) is bent in two concentric turns each having radius $\frac{r}{2}$. The self-inductance now is:

Self-inductance of a coil is $L \propto N^2 r$. When bent into $2$ turns of radius $r/2$, new self-inductance is $L' \propto (2)^2 (r/2) = 2 L$.

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Question 8:

easy

Assertion (A): The self inductance of a solenoid can be increased by decreasing length if number of turns are fixed.

Reason (R): Self inductance of a solenoid is directly proportional to current passing through it.

Self inductance of a solenoid is given by $L = \frac{\mu_0 N^2 A}{l}$. So, Assertion (A) is true as $L$ is inversely proportional to $l$. Self inductance $L$ is a property of the coil's geometry and material, not dependent on current. So, Reason (R) is false. Thus, (A) is true but (R) is false.

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Question 9:

moderate

Which among the following unit represents henry?

From induced emf $e = L \frac{di}{dt}$, we have $L = \frac{e dt}{di}$. Thus, the unit of inductance (henry) is equivalent to $\frac{\text{Volt-second}}{\text{Ampere}}$.

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