Chapter09 Series, Parallel, and Series Parallel Circuits PDF

 

CHAPTER 9 : SERIES, PARALLEL, AND SERIES-PARALLEL CIRCUITS

1. Three resistors, of 8.4 Ω, 6.8 Ω, and 4.8 Ω, are connected in series across a 100-V supply. Find (a) the total resistance, (b) the current, and (c) the voltage-drop across each resistor. [Answer: (a) 20 Ω; (b) 5 A. (c) 42 V, 34 V, and 24 V] 2.

What resistance must be connected in parallel with one of 1 Ω to give a combined

resistance of 0.2 Ω? [Answer: 0.25 Ω] 3. Three resistors, connected in parallel, have a combined resistance of 1.2 Ω. If the values of two of the resistors are 6 Ω and 12 Ω, what is the value of the third? [Answer: 1.71 Ω] 4. A resistor of 3.6 Ω is connected with another of 4.56 Ω. What value resistor must  be connected in parallel with the 3.6 Ω resistor, so that the combined resistance of the complete circuit will become 6 Ω? [Answer: 2.4 Ω] 5.

Find the equivalent resistance of the following circuit:

[Answer: 3.2 k Ω] 6.

Find the equivalent resistance of the following circuit:

[Answer: 1.25 k Ω] 7.

Two resistors of 4 Ω and 6 Ω, are connected in parallel. If the total current drawn

 by the circuit is 30 A, what is the value of the current through each of the resistors? [Answer: 18 A and 12 A]

 

  8. A coil of resistance 4 Ω has a shunt-resistance of 0.005 Ω connected in parallel with it. If the supply current is 50 A, what wh at is the value of the current in the coil? [Answer: 62.25 mA] 9. Two identical coils, each of resistance 100 Ω, are connected in series across a 200-V supply. What resistance must be connected in parallel with one of the coils in order to reduce the voltage across that coil to 95 V? [Answer: 950 Ω] 10. A resistor of 8 Ω is firstly connected in parallel with one of o f 12 Ω, and this combination is connected in series with a resistor of 4 Ω, and a voltage of 10 V applied across the circuit. The circuit is now reconnected, so that the 8- Ω resistor is now connected across the 4-Ω resistor. Find the voltage now necessary to produce the same value of current through the 8-Ω resistor. [Answer: 30 V] 11. For the following circuit, find the potential at points A, B, C, and D with respect to earth.

[Answer: (A) +30 V; (B) 0 V; (C) –20 V; (D) –70 V] 12. For the following circuit, find the potential at points A, B, C, and D with respect to earth.

[Answer: (A) +50 V; (B) +20 V; (C) 0 V; (D) –50 V]