Chapter 23 - Series and Parallel Circuits  
1. Why is it frustrating when one bulb burns out on a string of Christmas tree lights that are connected in series?
 
2. Why does the equivalent (total) resistance decrease as more resistors are added to a parallel circuit?
 
3. Several resistors with different values are connected in parallel.  The equivalent resistance will be less than which resistor?
 
4. Why is household wiring done in parallel instead of series?
 
5. What happens to the current in the other two lamps if one lamp in a three-lamp series circuit burns out?
 
6. What happens to the current in the other two lamps if one lamp in a three-lamp parallel circuit burns out?
 
7. If you have a 6 V battery and many 1.5 V bulbs, how could you connect them so they light but do not have more than 1.5 V across each bulb?
 
8. A 20.0 W lamp and a 5.0 W  lamp are connected in series and placed across a potential difference of 50 V.  What is:

 a.  The equivalent resistance of the circuit?
 b.  The current in the circuit?
 c.  The voltage drop across each lamp?
 d.  The power dissipated in each lamp?

9. Three identical lamps are connected in series to a 6.0 V battery.  What is the voltage drop across each resistor?
 
10. The load across a 12 V battery consists of a series combination of three resistors of 15 W , 21 W , and 24 W .

 a.  What is the total resistance of the load?
 b.  What is the current in the circuit?

11. The load across a battery consists of two resistors, with values of 15 W  and 45 W connected in series.

 a.  What is the total resistance of the load?
 b.  What is the voltage of the battery if the current in the circuit is 0.10 A?

12. A lamp having a resistance of 10 W  is connected across a 15 V battery.

 a.  What is the current through the lamp?
 b.  What resistance must be connected in series with the lamp to reduce the current to 0.50 A?

13. Three identical lamps are connected in parallel to each other and then connected to a 6.0 V battery.  What is the voltage drop across each lamp?
 
14. A 16.0  W  and a 20.0  W  resistor are connected in parallel.  A difference in potential of 40.0 V is applied to the combination.

a.  Calculate the equivalent resistance of the parallel circuit. 
b.  What is the current in the circuit? 
c.  How large is the current through the 16.0 W  resistor?

15. Compare the amount of current entering a junction in a parallel circuit with that leaving the junction.  Note: a junction is a point where three or more conductors are joined.
 
16. Explain the function of a fuse in an electric circuit.
 
17. What is a short circuit?  Explain why this is a dangerous situation.
 
18.

a.  Why does an ammeter have a very low resistance?
b.  Why does a voltmeter have a very high resistance?

19. Use the diagram below to answer the following questions:

a.  Calculate the equivalent resistance of the circuit.
b.  What is the current in the 8 W  resistor when a potential difference of 12 V is applied to the circuit?

   
 
20. A 20 W resistor, a 40 W resistor, and a 50 W resistor are connected in parallel across a 60 V power source.  Find the equivalent resistance of the set and the current in each resistor.
 
21. Use the diagram below to answer the following questions:

a.  Calculate the equivalent resistance of resistors R2 and R3.
b.  Calculate the equivalent resistance of R1, R2, and R3.
c.  Calculate the equivalent resistance of R1, R2, R3, and R4.
d.  A potential difference of 12 V is applied across the circuit.   Calculate the current through R4.
e.  Calculate the current through R1.