Given the RLC circuit with no power supply has R = 6.2ohm resistor,12H indutor and a .25μF
capacitor with an initial charge of 3.2μc and an initial current of 6.2mA in the direction of the charging capacitor.
(a)The value of charge in the capacitor is given by q = cv or v = q/c
or v = 3.2 x 10-6/0.25 x 10-6 = 3.2/0.25 = 12.8volt.
As there is no power supply in the RLC circuit,therefore angular frequence of a power supply
w = 0 and therefore there will be no inductive and capacitive reactance in the circuit.Therefore
the resistance offered by the circuit is only due to the resistor.
Therefore the maximum voltage in the circuit is given by
Vmax= Imax x R or Imax= Vmax/R or Imax = 12.8/6.2 = 128/62 = 2.06ampere.
To calculate the angle φ we can use the relation cosφ = R/Z,where cosφ is also called the power factor of the RLC circuit.
As there is no power supply in the circuit therefore the impedance of the circuit is due to only the resistor.
Therefore cosφ = R/R = 1 or φ = cos^-1(1) or φ = 0degree.
(b)The current at t = 1.25s is 2.06ampere as there is no power supply in the circuit.