1. Example Question 2
Referring to the circuit diagram: a resistor of 50 Ω is
connected in series with an 0.2H inductor that has a
resistance of 4 Ω. This circuit is powered from a 50Hz supply.
A voltage drop of 25V is measured across the resistor. Find:

2. (a) the current in the circuit
(b) the inductive reactance of the inductor
(c) the applied voltage
(d) the phase angle between the current and
the applied voltage

3. Values;
R1 = 50Ω
VR1 = 25V
L = 0.2H
f = 50Hz
RL = 4Ω

4. I =
25 = 0.5 A
50
Answer I = O.5A

5. XL = 2 π f L
XL = 6.28 x 50 x 0.2 = 62.8 Ω
Answer XL = 62.8Ω

6. L

7. L

8. Req = R1 + RL = 50 + 4
Req = 54 Ω

9. Therefore, VReq = I X Req = 0.5 x 54
VReq = 27V

10. So, VL = IL x XL = 0.5 x 62.8
VL = 31.4V

11. 27V 31.4V
L

12. 31.4
27

13. V = √(27² +31.4²)
V = √729 + 985.96 = √1714.96 = 41.4 V
Answer V = 41.4V

14. Adjacent
cos Φ =
Hypotenuses

15. Φ = Cos-¹
27 = 49.3⁰
41.4
Answer Φ = 49.3°