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Chapter 9 – Circuits Designed to Control Transfer of Electrical
Energy
Pages 304 - 327
Name: _____________________
Date: ____________
Block: ________
Section 9.1 – Series and Parallel Circuits
1. Define series circuit: ________________________________________________
2. Who invented the first light bulb that could be used in homes? ________________
3. In a series circuit, the total voltage is equal to the ___________ of voltages lost
at each ____________. This is because ___________________________________
4. Most electrons flowing in a circuit remain fairly evenly spread apart. In a series
circuit, the current in each part of the series is _______________.
5. What happens when resistors are added to a series circuit? __________________
____________________________________________________________________
6. Define parallel circuit: _______________________________________________
7. In parallel circuits, loads that are in parallel will have the same ______________
8. In a parallel circuit, the total current entering a _________________ must equal
the sum of the current leaving the junction point. A pathway with less
___________ will be able to have more electrons travel on it and therefore will
have a greater ___________ than the pathway with more ______________.
9. If you add a resistor in a parallel circuit to an existing resistor, what happens to
the total resistance in the circuit? ________________________________________
Circuit Diagram Practice
Draw the schematic diagram which corresponds to the circuit described.
Remember:
 An ammeter is always connected in series with the section of the circuit you are
measuring the current of.
 A voltmeter is always connected in parallel with the section of the circuit that you
are trying to measure the voltage difference of.
Example:
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1. One cell, one switch, an ammeter, and one bulb.
2. Two cells in series, two lamps in series and an open switch. If the cells were 1.5 V
each, what will the voltage in this circuit be?
3. Two cells in parallel and two lamps in parallel. If the cells were 1.5 V each, what
will the voltage in this circuit be?
4. Two cells in series, three lamps in series, one switch and a resistor. Place an
ammeter measuring the current reading entering the lamps.
5. Two cells in series, one bulb in series and two resistors in parallel. Place a
voltmeter measuring the potential difference across the two cells.
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6. Two cells in series, two lamps in parallel, and two resistors in parallel. Place an
ammeter in the circuit that measures the current entering the lamps.
7. Find the unknown voltage at V, and current at A, in each of the following circuits.
Voltage = ____________
Current = ____________
8. Find the unknown voltage at V, and current at A, in each of the following circuits.
Voltage = ____________
Current = ____________
Section 9.2 – The Power of Electricity
1. Define power: ______________________________________________________
2. What is the unit for measuring energy or work? __________________________
3. The unit for power is called the ______________ ( ), which is one joule (J) of
energy transformed in one ______________ (s).
4. What is an older unit of power called? Who invented this term? What does one
unit of horsepower equal to in watts? ____________________________________
5. Define electrical power: _____________________________________________
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6. Power of electrical devices is written as P = VI. State what each of the
following represents and their units.
a. P = ________________________
b. V = ________________________
c. I = ________________________
7. Power Problems
a) A toaster draws 5A of current from a 120V circuit. What is the power of the
toaster?
b) What is the power of a light bulb if a current of 500mA goes through it with a
voltage of 120V?
c) A 100W light bulb is operating on 1.2 amperes of current. What is the voltage?
d) A potential difference of 120 volts is operating on a 500 watt microwave oven.
What current is being used?
e) If a computer has a resistance of 100 ohms and runs on normal household
electricity (120 V), what is the computer’s electrical power rating? (Hint: you will
need Ohm’s law also)
f) What is the resistance of a kettle if it uses 4800 W of power on normal household
electricity?
8. Define power rating: ________________________________________________
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9. What does a power rating of 40 W mean in terms of energy and time? __________
____________________________________________________________________
10. What is the formula that relates energy consumption (E) to power (P) and time
(t)? Include units for each.
11. Convert the following times into seconds. Remember 1 minute = 60 seconds and 1
hour = 60 minutes. Show your work.
a) 6.0 minutes
=
= _______________ s
b) 20 minutes
=
= _______________ s
c) 2 hours
=
= _______________ s
12. Energy Consumption Problems
a) How much electrical energy is consumed by a 60 W light bulb if it is left on
for 25 minutes?
b) A 1600 W kettle is turned on for 3.0 minutes. How much electrical energy
does the kettle use in this time?
c) How much electrical energy is consumed by a 100 W light bulb left on for 4.0
hours?
13. What unit of energy is commonly used when dealing with large quantities of
energy? _____________________________________________
14. Calculating Electrical Energy and Cost
a) How much kW*h of electricity is consumed by a 1000 W light bulb that burns for
three hours?
b) A 3000 W toaster is used for 15 minutes. How many kW*h of electricity did it
consume?
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c) A 4400 W electric stove operates for 1 hour. What is the cost to run the electric
stove if the cost of energy is $0.10/kW*h?
d) A 10,000 W space heater runs for 2 days. If electricity costs $0.05/kW*h, what did
it cost to run the heater this long?
e) A microwave oven operates on 5 amps of current on a 110 V circuit for 1 hour.
How much would it cost to run the microwave if the cost of energy is $0.10/kW*h?
f) The meter reading on June 1 was 84502 kW*h. On July 1, the meter read 87498
kW*h. If the cost of electricity in the area was 12¢ per kW*h, what was the electric
bill for the month of June?
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