Initially the circuit of Figure 1 is \"driven\" by a DC source V of value 12 volts as shown in Figure 1. Note that before switch closure the circuit has been active long enough to ensure DC steady state conditions t-0 Ri R4 V4 Vc Figure 1 Com nent values R 60 ohms C 3200 microfarads V 12 volts R2 388 ohms R3 100 ohms R4 33 ohms The DC source is now replaced with a sinusoidal ac source V Vm.cos(et) where the frequency fis 60Hz and Vm 24 volts (peak value). The switch is closed and the circuit allowed to settle to ac steady state conditions (7) Determine the steady state reactive power in vars associated with the capacitor C (8) Determine the average power dissipated in resistor R2 in milliwatts (9) Determine the average power dissipated in resistor R3 in watts (10) Determine the apparent power delivered by the sinusoidal voltage source V in volt amperes Solution 1) Power is not consumed by Capacitors i.e. Zero Capacitor becomes open and R 3 is short circuited 2) Average power in R 2 = V RMS x I RMS = V 2 RMS /R Voltage across R 2 = V x 88/(88+60+33) = 0.486 V = 11.66 volt RMS value = 11.66/1.414 = 8.25 volt Average power in R 2 = 8.25 x 8.25/88 =0.773 watt 3) Average power in R 3 = 0 because it is short circuited and voltage across R 3 is zero .

1. Initially the circuit of Figure 1 is "driven" by a DC source V of value 12 volts as shown in
Figure 1. Note that before switch closure the circuit has been active long enough to ensure DC
steady state conditions t-0 Ri R4 V4 Vc Figure 1 Com nent values R 60 ohms C 3200
microfarads V 12 volts R2 388 ohms R3 100 ohms R4 33 ohms The DC source is now replaced
with a sinusoidal ac source V Vm.cos(et) where the frequency fis 60Hz and Vm 24 volts (peak
value). The switch is closed and the circuit allowed to settle to ac steady state conditions (7)
Determine the steady state reactive power in vars associated with the capacitor C (8) Determine
the average power dissipated in resistor R2 in milliwatts (9) Determine the average power
dissipated in resistor R3 in watts (10) Determine the apparent power delivered by the sinusoidal
voltage source V in volt amperes
Solution
1) Power is not consumed by Capacitors i.e. Zero
Capacitor becomes open and R 3 is short circuited
2) Average power in R 2 = V RMS x I RMS = V 2
RMS /R
Voltage across R 2 = V x 88/(88+60+33) = 0.486 V = 11.66 volt
RMS value = 11.66/1.414 = 8.25 volt
Average power in R 2 = 8.25 x 8.25/88 =0.773 watt
3) Average power in R 3 = 0 because it is short circuited and voltage across R 3 is zero