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CG PET Self Inductance — practice questions

Explore 6 free Self Inductance questions in CG PET Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Self Inductance questions and exercises with answers

Showing questions 1–6 of 6.

The SI unit of self-inductance $L$ is:Read the answer and worked solution →The induced EMF in a coil due to changing current in itself is given by:Read the answer and worked solution →The self-inductance of a long solenoid with $n$ turns per unit length, cross-section $A$ and length $\ell$ is:Read the answer and worked solution →A solenoid of $N = 200$ turns, length $L = 20$ cm and cross-section $A = 5\ \text{cm}^2$ has self-inductance approximately:Read the answer and worked solution →A current of 4 mA in a coil of self-inductance 10 mH and 200 turns produces total flux:Read the answer and worked solution →If the current in a coil of inductance 5 H changes from 2 A to 5 A in 0.1 s, the magnitude of induced EMF is:Read the answer and worked solution →

Worked practice questions

The SI unit of self-inductance $L$ is:

  1. weber (Wb)
  2. tesla (T)
  3. ohm (Ω)
  4. henry (H)
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Correct answer: D. henry (H)

From $e = -L\,dI/dt$, units of $L$ = V/(A/s) = V·s/A = henry (H). One henry is the inductance that produces 1 V of EMF when current changes at 1 A/s.

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The induced EMF in a coil due to changing current in itself is given by:

  1. $e = -L\,dI/dt$
  2. $e = +L\,dI/dt$
  3. $e = L/I$
  4. $e = L \cdot I$
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Correct answer: A. $e = -L\,dI/dt$

**Self-induced EMF:** $e = -L\,dI/dt$. The minus sign (Lenz) means it opposes the change in current, hence the description of self-inductance as 'electrical inertia'.

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The self-inductance of a long solenoid with $n$ turns per unit length, cross-section $A$ and length $\ell$ is:

  1. $\mu_0 n \ell A$
  2. $\mu_0 n^2 \ell A$
  3. $\mu_0 n^2 / (\ell A)$
  4. $\mu_0 n A / \ell$
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Correct answer: B. $\mu_0 n^2 \ell A$

$L = \mu_0 n^2 \ell A$ (with $\ell A$ = interior volume). Derived from $L = N\phi_B/i$ using $B = \mu_0 n i$.

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