Download Lab: Ohm`s Law

OHM’S LAW
e
on
In 1827 a German physicist, Georg Ohm, studied electrical resistance of many substances. From these
studies he was able to show a relationship among three factors in a circuit: voltage, current, and
resistance. In most circuits, voltage, current, and resistance follow a simple relationship. This relationship
is known as Ohm’s Law. In this investigation you will learn about the relationship between voltage,
current, and resistance in order to complete calculations using Ohm’s Law.
Objective
When you have completed this investigation you should be able to complete calculations using Ohm’s Law
in order to explain the relationships among current, voltage, and resistance.
Activity 1:
Pre-Reading
1. Use prior knowledge to define the following terms.
__________________________________
_________________________________________
Current (
)-
__________________________________
_________________________________________
Voltage(
)-
_________________________________
_________________________________________
Resistance(
)-
2. Identify the symbols and units for each of the above terms and write them next to the definitions.
Activity 2:
During Reading
1. Read pages 60-61 in Prentice Hall, Science Explorer: Electricity and Magnetism. Write any
questions that you have in the space below.
135
2. Reread and take notes on the mathematical formulas and relationships in Chart 1, “Ohm’s Law Notes.”
Ohm’s Law Notes
Mathematical Equations
Activity 3:
Relationships
After Reading
1. Calculate and complete Chart 2, “Ohm’s Law Calculations,” using Ohm’s Law.
Chart 2
Ohm’s Law Calculations
Voltage (V)
1.5
1.5
3.0
6.0
9.0
Current(A)
0.3
.05
Resistance(Ω)
30
15
30
0.15
15
2. Explain what happens in a circuit that obeys Ohm’s Law if the resistance is doubled and the voltage
remains the same. Use information from the investigation to support your response.
136
3. Explain what happens to current if voltage is tripled and resistance is cut in half. Use information from
the investigation to support your response.
4. Explain how the graphic organizer below could be helpful in remembering the relationships and
mathematical formulas for Ohm’s Law. Use evidence from the investigation to support your response.
V
I
R
137