Question

4:33 < Back Final Assignment copy ☺ Ouestion 2: a) A 22 nF capacitor in series with a 3.9k12 resistor is put across 40V, 1 kHz supply as shown in figure). Determine the current in the circuit. (4 Marks) b) A 2uF capacitor, 100 A resistor and 8H inductor are connected in series with an AC source. If the r.m.s value of the voltage source is 200 V at 50 HZ, then calculate the phase difference between voltage and current. Also calculate phase difference at maximum current. (5+1-6Marks)

Answer 1

1) capacitance C=22nF

resistance =3.9kohm

voltage V=40V

frequency f= 1kHz

impedence Z=$\sqrt{R^{2}+Xc^{2}}$ =$\sqrt{R^{2}+(1/2\pi fc)^{2}}$=$\sqrt{3900^{2}+(1/2\pi 1000x22x10^{-9})^{2}}$ =8218.6ohm

current I = V/Z =40/8218.6ohm =4.867x10-3ampere

2)capacitance C=2x10-6F

resistance =100ohm

inductance L=8H

voltage V=200V

frequency f= 50Hz

phase difference $\phi$ = cos-1 (R/Z)

impedence Z =$\sqrt{R^{2}+(XL-Xc)^{2}}$ =$\sqrt{R^{2}+(2\pi fL-1/2\pi fc)^{2}}$ =

$\sqrt{100^{2}+(2\pi 50x8-1/2\pi 50x2x10^{-6})^{2}}$ =927.1ohm

phase difference $\phi$ = cos-1 (R/Z) = cos-1 (100/927.1)=820