Class 12 Physics Alternating Current LC oscillations

LC oscillations

  • LC  circuit consists of an inductor and a capacitor connected in a series.
  • Consider a circuit with a capacitor and an inductor, energy taken from the cell  and given to capacitor keeps oscillating between L & C.
  • The  oscillations  between L and C  are referred as  LC  oscillations.
  • When AC  voltage  is  applied  to  the  capacitor, it  will first  charge  and then will discharge ,again  will  charge and  discharge  and  this  process  will keep on continuing.
  • When the  capacitor is  fully charged  it will start discharging  and the charge is transferred to the inductor which is connected to the capacitor.
  • Because  of  change  in  the current  there  will be  change in  the magnetic flux  of the inductor in the circuit.
  • As a result there will be an emf induced in the inductor.
  • The EMF is given by e = - L (dI/dt). The self-induced emf will try to oppose the growth of the current.
  • As a result when the capacitor gets completely discharged all the energy stored in the capacitor will now be stored in the inductor.
  • The capacitor will become fully discharged whereas inductor will be storing all the energy.
  • As a result now the inductor will start charging the capacitor. The energy stored in the capacitor will start again increasing .
  • This cycle will keep on continuing.
  • These oscillations are known as LC  oscillations. Electric field energy and magnetic field  energy will keep oscillating.

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