Electric Current- A flow of electric charges is an electric current.
22 Electric Current - Humble Independent School District · MAINIDEA Explain how charged particles...
Transcript of 22 Electric Current - Humble Independent School District · MAINIDEA Explain how charged particles...
22 Electric CurrentBIGIDEAWrite the Big Idea for this chapter.
Use the “What I Know” column to list the things you know about the Big Idea. Then list the questions you have about the Big Idea in the “What I Want to Find Out” column. As you read the chapter, fill in the “What I Learned” column.
KWhat I Know
WWhat I Want to Find Out
LWhat I Learned
Science Notebook • Electric Current327
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22 Electric Current 1 Current and Circuits
MAIN IDEAWrite the Main Idea for this lesson.
Recall and write the definition of the Review Vocabulary term.
electric potential difference
Use your book to define each term.
electric current
conventional current
battery
electric circuit
ampere
resistance
resistor
parallel connection
series connection
REVIEW VOCABULARY
electric potential
difference
NEW VOCABULARY
electric current
conventional current
battery
electric circuit
ampere
resistance
resistor
parallel connection
series connection
5(F)
Science Notebook • Electric Current328
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Vendor: LASERWORDS Grade: N/A
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-Hill Education. Perm
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1 Current and Circuits (continued)
Explain how you can maintain a potential difference between two plates connected by a conductor.
Draw a flow chart showing how a water wheel transforms potential energy into work done by a motor.
GET IT? Draw a diagram of an electric circuit, and explain how energy is conserved in it.
GET IT? Restate the equations for power using the variables: energy (E), charge (q), and current (I).
Student Edition, pp. 598–600
Science Notebook • Electric Current329
Program: TX HS Science Component: PPP SCI NTBKPDF PASS
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1 Current and Circuits (continued)
TRY IT!
Problem
ELECTRIC POWER AND ENERGY A 12.0-V battery delivers a 0.75-A current to an electric motor connected across its terminals.
a. What power is delivered to the motor?
b. If the motor runs for 5.0 min, how much electrical energy is delivered?
1. ANALYZE AND SKETCH THE PROBLEM
KNOWNS UNKNOWNS
ΔV =
I =
t =
= ?
= ?
2. SOLVE FOR THE UNKNOWN
a. Use P = IΔV to find power.
b. Use the relationship between energy and power.
3. EVALUATE THE ANSWER
• Are the units correct?
• Is the magnitude realistic?
Student Edition, p. 601
Use with Example Problem 1.
Use this column for
scratch work and
sketches.
Science Notebook • Electric Current330
Program: TX HS Science Component: PPP SCI NTBKPDF PASS
Vendor: LASERWORDS Grade: N/A
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-Hill Education. Perm
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GET IT? Explain how a schematic of an electric circuit compares to an artist’s drawing of the same circuit.
GET IT? Identify what an ammeter and a voltmeter measure.
Draw symbols for the following elements commonly found in electric circuit diagrams.
Ammeter Ground
Battery Lamp
Capacitor Resistor
Fuse Voltmeter
Student Edition, pp. 602–603
1 Current and Circuits (continued)
Science Notebook • Electric Current331
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Student Edition, pp. 604–606
1 Current and Circuits (continued)
GET IT? Define resistance in your own words.
Describe how resistance changes when each of the physical factors in the table increases.
Length
Cross-sectional area
Temperature
GET IT? Explain which devices obey Ohm’s law.
GET IT? List two ways to control the current flowing through a simple circuit.
Evaluate If a variable resistor decreases the amount of wire in a circuit that contains a motor, what happens to the speed of the motor?
Science Notebook • Electric Current332
Program: TX HS Science Component: PPP SCI NTBKPDF PASS
Vendor: LASERWORDS Grade: N/A
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-Hill Education. Perm
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1 Current and Circuits (continued)
Student Edition, pp. 607–608
Use with Example Problem 2.
Use this column for
scratch work and
sketches.
TRY IT!
Problem
CURRENT THROUGH A RESISTOR A 12.0 V battery is connected to a 15.0-Ω resistor. What is the current in the circuit?
1. ANALYZE AND SKETCH THE PROBLEM
KNOWNS UNKNOWN
ΔV =
R =
= ?
2. SOLVE FOR THE UNKNOWN
Use I = ΔV _ R
to determine the circuit.
3. EVALUATE THE ANSWER
• Are the units correct?
• Is the magnitude realistic?
Draw a parallel and a series circuit in the boxes below.
Parallel circuit Series circuit
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Fill in the blanks in the sentence about different types of electrical connections.
The terms voltage across are associated with a
connection, while the terms current through are associated with a
connection.
1 Current and Circuits (continued)
Student Edition, p. 608
SUMMARIZE
How does the MAINIDEA for this section relate to the chapter’s BIGIDEA?
REVIEW IT!
19. MAINIDEA Explain how charged particles are related to electric current, electric circuits, and resistance.
20. Schematic Draw a schematic diagram of a circuit that contains a battery and a lightbulb. Make sure the lightbulb will light in this circuit.
Science Notebook • Electric Current334
Program: TX HS Science Component: PPP SCI NTBKPDF PASS
Vendor: LASERWORDS Grade: N/A
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21. Resistance Joe states that because R = ΔV _ I , if he increases the voltage, the resistance
will increase. Is Joe correct? Explain.
22. Power A circuit has 12 Ω of resistance and is connected to a 12-V battery. Determine the change in power if the resistance decreases to 9.0 Ω.
23. Resistance You want to measure the resistance of a long piece of wire. Show how you would construct a circuit with a battery, a voltmeter, an ammeter, and the wire to be tested to make the measurement. Specify what you would measure and how you would compute the resistance.
24. Energy A circuit transforms 2.2×103 J of energy when it is operated for 3.0 min. Determine the amount of energy it will transform when it is operated for 1 h.
25. Critical Thinking We sometimes say that power is “dissipated” in a resistor. To dissipate is to spread out or disperse. In what sense is something being dispersed when charge flows through a resistor?
1 Current and Circuits (continued)
Science Notebook • Electric Current335
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