CBSE Class 12-science Physics Alternating Current
AC Applied Across Resistor
1. When an alternating voltage V = V_m sinwt is connected to a resistor R, the current through it is given by as I = im sin wt and Vm = imR.
2. The current is in phase with the potential difference in an AC circuit with onlyandnbsp; resistors.
AC Applied Across Capacitor1. On connecting a capacitor to an AC source it repeatedly gets charged, discharged and then charged in the opposite direction.
2. The capacitive reactance Xc= 1/andomega;C.
3. The current leads the voltage by 90 degrees in AC circuit with capacitor.
4. Voltage amplitude is equal to current amplitude times the capacitive reactance. Vm= I Xc
AC Applied Across Inductor1. In an AC circuit with an inductor, the current lags behind the voltage by 90 degrees.
2. The inductive reactance XL= wL where w is the angular frequency of the AC source.
3. The peak value of current is given by Im = Vm/ XL
4. SI unit of reactance is ohms.
5. Higher the frequency of the AC source, more the inductive
AC Applied to LCR in SeriesCurrent in a series LCR circuit with an AC emf. Impedance of the LCR circuit, phase constant of the circuit.
Resonance in LCR CircuitResonant frequency, impedance and current at resonance. Quality factor of the circuit.
Power in AC CircuitRoot mean square current, average power, power factor