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Name ____________________________ Date ____________________ Class ____________
Electricity
■
Guided Reading and Study
Electric Circuits
This section explains what Ohm’s Law is. It also describes the basic features of an electric circuit
and explains what series and parallel circuits are.
Use Target Reading Skills
As you read, compare and contrast series circuits and parallel circuits in the Venn diagram
below. Write the similarities in the space where the circles overlap and the differences on the left
and right sides.
Parallel
Circuit
Series
Circuit
a.
b.
Only one path
for current to take
Ohm’s Law
1. Who performed experiments in the 1800s that demonstrated how current, voltage,
and resistance are related?
_________________________________________________________________________
2. Ohm’s law says that ________________________ is equal to the voltage divided by
the current.
3. Write the equation for Ohm’s law.
_________________________________________________________________________
_________________________________________________________________________
4. Rearrange the equation from Question 3 so that it finds voltage instead of resistance.
_________________________________________________________________________
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
Name ____________________________ Date ____________________ Class ____________
Electricity
■
Guided Reading and Study
5. In a circuit, there is a 0.8 A current in the bulb. The voltage across the
bulb is 4.0 V. What is the bulb’s resistance?
_________________________________________________________________________
6. A 10-A current is in the heating coils of a toaster. If the resistance of the
coils inside the toaster is 12 Ω, what must the voltage be?
_________________________________________________________________________
7. Is the following sentence true or false? For the same resistance, the
greater the voltage, the greater the current. _________________________
Features of a Circuit
8. What are the three basic features all electric circuits must have?
a. _____________________________________________________________________
_____________________________________________________________________
b. _____________________________________________________________________
c. _____________________________________________________________________
_____________________________________________________________________
9. Why are devices run by electrical energy represented as resistors in a
circuit?
_______________________________________________________________________
_______________________________________________________________________
10. Circle each example of a source of electrical energy.
a. battery
b. computer
c. electric plant
d. generator
11. Why is a switch often included in a circuit?
_______________________________________________________________________
12. Label each symbol used in the circuit diagram by filling in the blanks.
a.
+ –
b.
current
c.
d.
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
Electricity
_____________________________________________________________________
Name ____________________________ Date ____________________ Class ____________
Electricity
■
Guided Reading and Study
Electric Circuits (continued)
Series Circuits
13. What is a series circuit?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
14. In a series circuit, how many paths are there for a current to take?
________________________
15. Suppose you have a number of light bulbs connected together in a series
circuit. What happens if one of the bulbs burns out?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
16. As more light bulbs are added to a series circuit, the bulbs become
dimmer. Why?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
17. If you wanted to measure the current through some device in a circuit,
how would you connect an ammeter?
_________________________________________________________________________
_________________________________________________________________________
Parallel Circuits
18. If different parts of a circuit are on separate branches, the circuit is called
a(n) ________________________.
19. Suppose you have a number of light bulbs connected on a circuit, with each
bulb on a separate branch. What happens if one of the bulbs burns out?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
Name ____________________________ Date ____________________ Class ____________
Electricity
■
Guided Reading and Study
20. Circle the letter of each sentence that is true about what happens when
more branches are added to a parallel circuit.
a. Resistance increases.
b. The current has more paths to follow.
c. Resistance decreases.
d. The current has fewer paths to follow.
21. Is the following sentence true or false? Adding more paths to a parallel
circuit will increase the current. ________________________
22. Identify each of the circuits shown here by writing the type of circuit on
the line.
Electricity
a.
b.
23. If you wanted to measure the voltage in a parallel circuit, how would
you connect the voltmeter?
_________________________________________________________________________
_________________________________________________________________________
24. Why wouldn’t you want the circuits in your home to be series circuits?
_________________________________________________________________________
_________________________________________________________________________
25. What kind of circuit provides a path for current to wall sockets and
appliances in a home? ________________________
26. The voltage in most household circuits is ________________________.
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.