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MERLOT II


    

Learning Exercise


Material: Ohm's Law
Submitted by: Terry Bradfield on Jul 25, 2002
Date Last Modified: Jul 26, 2002
Title: Ohm's Law Worksheet
Description: This is a worksheet for non-science majors that explores the meaning of Ohm's law.
Type of Task: Individual, Student-centered, Unsupervised
Time Required Approximately 1/2 hr.
Topics: Ohm's law and resistance
Audience: College General Ed, High School
Categories:
Prerequisites Skills: Students should be familiar with the definitions of basic electrical quantities.
Learning Objectives: To understand the physical meaning of Ohm's law.
Text of Learning Exercise:

Ohm's Law Worksheet



Introduction


An electric circuit is a closed loop around which electric charge flows.
A source of electrical energy (such as a battery) is required to maintain
the flow. An simple electric circuit consists of a battery with its terminals
connected by one or more conducting elements. In the first part of this experiment,
you will attempt to verify Ohm's law for a single element:

V = IR


Where V is the emf (voltage), I is the current, and R
is the resistance of the conducting element.The applet for this experiment
is located at: 
http://www.shep.net/resources/curricular/physics/java/physengl/ohmslaw.htm.


Procedure



Measurements






Before attempting any measurements, you have to choose a measurement range. 
Set the maximum voltage to 10 V and the maximum amperage to 300 mA. Use the
buttons to set the resistance to 30 W. Now you
are ready to begin your measurements. Use the voltage buttoms to step the
voltage values from 1 V through 7 V in 1 V steps. For each applied voltage,
record the current in the table below and calculate the ratio V/I.

Current Measurements for a 30.0 W resistance.


































Voltage, in volts (V)
1.00


2.00


3.00


4.00


5.00


6.00

Current, in amperes (I)            
Resistance R = V/I            


Average value of R = _____________.


Next, change the resistance to 60 W and repeat
the process above.



Current Measurements for a 60 Wresistance.



































Voltage, in volts (V)
1.00


2.00


3.00


4.00


5.00


6.00

Current, in amperes (I)            
Resistance R = V/I            


Average value of R = _____________.

& nbsp;


Questions


1. How do the currents in the two resistances compare for the same applied
voltage? ___________________________________________________

 

2. What current would you expect in a 90 W
resistance when a 4.00 V potential is applied? ___________________

 



 

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