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6. Electromagnetic induction — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics6. Electromagnetic induction1 Mark
MCQ
For $L-R$ circuit, the time constant is equal to
  • ✓
    twice the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance
  • B
    ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance
  • C
    half the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance
  • D
    square of the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance
✓

Answer

Correct option: A.
twice the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance
a
The time required for the current flowing in the $LR$ series circuit to reach its maximum steady state value is equivalent to about $5$ time constants or $5 \tau$. This time constant $\tau$, is measured by $\tau=L / R$, in seconds, where $R$ is the value of the resistor in ohms and $L$ is the value of the inductor in Henries

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