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Physics Lesson Plan
Teacher
Howard
Unit Title
Length
Goal(s)/PLO(s):
Course
Grade Level
Block/Period
 draw and interpret circuit diagrams
 construct circuits from schematic diagrams
 demonstrate the correct placement and use
of an ammeter and voltmeter
 define electromotive force (emf), terminal
voltage, and internal resistance
Phys 12
12
Date
Class Size
Lesson #, of
19-08
 solve problems using
– terminal voltage
– electromotive force (emf)
– internal resistance
– current
– electric potential difference
Materials:
Ammeters and Voltmeters
Timeline
Class Activities
Introduction
Body
Notes 19-08
Closure
Questions 20-24 , Problems 53-61odd
19-08 Ammeters and Voltmeters
Ammeter
• device used to measure current
Voltmeter
• device used to measure potential difference or voltage
Analog meters
• a pointer moves along a
scale
Digital meters
• display the numerical value in
numbers
The analog meters have a galvanometer inside them for which the
amount of current passing through the device determines how
much the needle deflects.
In the ammeter there is a parallel circuit so only a fraction of the
current passes through the galvanometer and the rest goes through
the shunt resistor (very low resistance) so it doesn’t break and
there is minimal impact on the circuit.
The ammeter must be connected in series to function.
An analogue voltmeter is also a galvanometer and a resistor but
they are connected in series and the resistance is very large so that
very little current passes through the voltmeter.
In order to have a minimal effect on the circuit (not stop the flow
of current) the voltmeter must be placed in parallel around a
resistor or battery
A potentiometer can measure the voltage without having any
current pass through it.
Multimeters
• have a variety of shunt or series resistors so the galvonometer
can give a reading for a variety of currents and voltages
Ohmmeters
• measure resistance by measuring the current through a
resistor using a built in battery of known voltage
• can damage the device if it sends too much current
Making a measurement on a circuit changes the circuit
Example 19-15
Digital meters are more precise (not necessarily accurate,
depending on what is being measured) and will have less of an
effect on the circuit.
Question 20-24 no problems