Transcript Chapter 8: Electrical Relationships

Integrated Science
Unit 3, Chapter 8
Unit Three: Electricity and Magnetism
Chapter 8 Electrical Relationships
8.1
Ohm's Law
8.2
Work, Energy, and Power
Chapter 8 Learning Goals
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Measure how current changes when voltage is increased.
Measure how current changes when resistance is increased.
Describe how voltage, current, and resistance are related.
Use Ohm’s law to solve circuit problems.
Explain why resistors are used in a circuit.
Define power as the rate at which energy flows.
Describe relationships between work, energy, and power.
Calculate power use in a circuit.
Rank the amount of power used by various household appliances.
Estimate the cost per month of using a common household
appliance.
Use dimensional analysis to find out what we buy from electric
utility companies.
Explain how to choose a safe extension cord.
Chapter 8 Vocabulary Terms
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horsepower
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kilowatt
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kilowatt-hour
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Ohm’s law
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potentiometer
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power
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resistor
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watt
8.1 Ohm's Law
Key Question:
How are voltage, current and resistance
related?
*Read text section 8.1
AFTER Investigation 8.1
8.1 Using Ohm's Law
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German physicist Georg Ohm
experimented with circuits to
find an exact mathematical
relationship between voltage,
current and resistance.
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Ohm's law can be used to
predict any one of the three
variable if given the other two.
8.1 Graphing and Ohm's law
8.1 Resistors
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Electrical components called
resistors can be used to control
current.
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Resistors have striped color
codes to record their "values"
(writing on them is difficult).
8.1 Electrical controls
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Potentiometers are a type of "variable" resistor that can
change from low to high.
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They are wired so that as you turn the knob, it changes the
distance the current has to flow.
8.2 Work, Energy, and Power
Key Question:
How much does it cost to
use the electrical
appliances in your home?
*Read text section 8.2
AFTER Investigation 8.2
8.2 Electric Power
 Power
is the rate at which
energy flows.
 Electric
companies charge a
rate for the energy you use.
 We
use "watts" as a standard
unit because energy can be
converted into many different
forms.
8.2 Electrical Power
voltage (volts)
Power (watts)
P = VI
current (amps)
8.2 Electricity, power, and heat