Name: _____________________
Wire Resistance and Ohm’s Law PhET MiniLab
Introduction: When an electrical potential exists in a circuit, a current may flow. Current is the flow of electrons in a circuit. Resistance in the circuit slows the flow of the electrons, reducing the current in the circuit. We will use the mathematical form of Ohm’s Law frequently when we investigate electric current and circuits later in this unit.

• Open the PhET Simulation Electricity, Magnets, and Circuits ( Resistance in a Wire[pic] As wire length (cm) increases, the resistance (Ω) _________________ As wire area (cm2) increases, the resistance (Ω) __________________ As wire density (Ωcm) increases, the resistance (Ω) _______________ Procedure: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law [pic] mA is milliamps, and _________ milliamps equals one Ampere.

• Move the potential (volts) and resistance (ohms) sliders and observe the current (amps) As voltage increases, current __________________.
As resistance increases, current ________________.
Fill out the tables below and check your work in the simulation. ( ½ pt each ) • Remember, the simulation shows milliamps.
• You should show Amperes
V =I * R
|8.0 V |A |800 Ω | |2.0 V |.044 A |Ω | |V |.0058 A |430 Ω | |V |.069 A |100 Ω | |6.4 V |A |300 Ω |

Conclusion Questions: ( ½ pt each)
1. Incandescent light bulbs have a very thin filament that glows when hot. Thin filaments have very high / low resistance. 2. The 12V battery in your car operates a 25 amp car stereo. What is the resistance of this stereo system? ___________ 3. A “2D” Maglite flashlight runs on 3.0V. What is the current through the bulb if resistance...

...Experiment No: EM-1 Title: Ohm’s Law, Meters, Resistivity
I Purpose:
The basic of simple electrical circuits and measurements is learned. Also, investigating the dependence of the resistance of a wire on its length, cross-sectional area, and the material of which it is made. By examining electrical resistance (R) through a metal conductor, the voltage (V) and current (I) through the conductor, the following principles will be demonstrated:
1.) Ohm’sLaw
2.) Dependence of resistance (R) on the length (L), cross-sectional area (A) and electrical resistivity (ρ) and volt, (V).
II Procedure:
Apparatus: DC power supply, milliammeters and ammeters, voltmeters, SPST switch, a “fused” connector, a 2-meter slide wire resistance, and mounted resistance spools.
Variation of V and I, with R held constant
1 Connect the apparatus as shown in the Figure below, attaching the voltmeter last.
Figure 1
2 Set the power to 4 volts. To begin with, set the voltmeter on the 0-5 volt rang and the milliammeter on the 0-1000 ma range.
3 Take a series of simultaneous voltage and current readings for currents I: 75, 150, and 225 milliamps.
4 Create a table and observe the value of the resistance and see if there is any constant.
Variation of V along a resistance wire, I constant
1. Connect the apparatus as shown in the Figure below.
Figure 2
2. Measure of V across various lengths L of the 2-meter wire between the 0 cm end and other...

...Name __________________________ Wire Resistance and Ohm’s Law
Go to http://phet.colorado.edu/simulations/sims.php?sim=Ohms_Law
and click on Run Now.
Wire Resistance and Ohm’s Law
Procedure Part I Wire Resistance:
open the PhET Simulation Electricity, Magnets, and Circuits ( Resistance in a Wire.
As wire length (cm) increases, the resistance (Ω) _increases________
As wire area (cm2) increases, the resistance (Ω) _decreases_________
As wire resistivity (Ωcm) increases, the resistance (Ω) _increases____
Procedure Part II: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law
mA is milliamps, and _1,000_____ milliamps equals one Ampere.
• Move the potential (volts) and resistance (ohms) sliders and observe the current (amps)
As voltage increases, current _increases__________.
As resistance increases, current _decreases (slows)__.
Fill out the tables below and check your work in the simulation. ( ½ pt each )
• Remember, the simulation shows milliamps.
• You should show Amperes
V = I * R
|8.0 V |.01 A |800 Ω |
|2.0 V |.044 A |450 Ω |
|0.2 V |.0058 A |430 Ω |
|6.9 V |.069 A |100 Ω |
|6.4 V |.0213 A |300 Ω...

...Investigating Ohm’s Law
Introduction/Background
Current is the rate of the flow of energy; an electric current is the flow of electrical charge around the circuit. It is measured in ohms (Ω). The quantity of flow in an electric circuit is dependent on the ohmic value of the resistance. The amount of resistance in a given circuit is stationary and is not dependent on the current. “The higher the voltage of a battery, the more potential energy per coulomb of charge it can supply.” (1)
It is observed (in an ideal circuit), that when all other elements maintain at a constant level, an increase in voltage will definitely mean an increase in the flow of electrons (current). As voltage increases, so does current so they have a positive relation to each other (Figure 1a.). In a non-theoretical circuit the light bulbs and wires increase the resistance as the current flows through the circuit, weakening the current itself (Figure 1b.).
However there is another variable observed, in the form of resistance. Resistance is the force acting against current; it impedes the flow of current. It is observed that, as more globes are added in a circuit the weaker the current flow. Therefore it can be deduced that as the resistance increases, the current decreases, this is an inverse relationship between the two variables. Materials with low resistance (e.g. metals) are called electrical conductors and materials with high resistance (like wood) are named...

...Research Paper – Georg Ohm
Georg Ohm was a German physicist born in March of 1789.
Georg came from a Protestant family. His father who was a locksmith Johann Wolfgang Ohm, and his mother who is Maria Elizabeth Beck, was the daughter of a tailor. Even though his parents had not been really educated at the time, Ohm's father was a very wise man who had educated himself and his son Georg.
In my research I found out that he wrote an elementary grade geometry book while teaching mathematics at several schools. Ohm began experimental work in a school physics lab after he had learned of the discovery of electromagnetism. Ohm gave a mathematical description of conduction in circuits modeled on Fourier's study of heat conduction. Ohm's well understanding of results from the experimental evidence and, he was able to suggest laws which really helped explain results of others working on galvanic electricity.
Ohm's Law - Using the results of his experiments, Georg Ohm was able to define the basic relationship between voltage, current, and resistance. The equation I = V/R is known as "Ohm’s Law". It states that the amount of steady current through a material is directly proportional to the voltage across the material divided by the electrical resistance of the material. The ohm (R), a unit of electrical resistance, is equal to that of a...

...OhmsLawOhmsLaw
Thomas More College
Thomas More College
How it applies to different materials
Lucas Cosmidis 11 physics
How it applies to different materials
Lucas Cosmidis 11 physics
Aim/Purpose
The aim is to investigate whether 12v light bulb and a ceramic resistor are either non- ohmic or ohmic. From results calculations can be made to find the resistance produced and then graphed indicating whether the light bulb and ceramic resistor is ohmic or non ohmic
Background Information
An electric circuit is formed when a conductive path is created to allow free electrons to continuously move. This continuous movement of free electrons through the conductors of a circuit is called a current, and it is often referred to in terms of "flow," just like the flow of a liquid through a hollow pipe.
The force motivating electrons to "flow" in a circuit is called voltage. Voltage is a specific measure of potential energy that is always relative between two points. When we speak of a certain amount of voltage being present in a circuit, we are referring to the measurement of how much potential energy exists to move electrons from one particular point in that circuit to another particular point. Without reference to two particular points, the term "voltage" has no meaning.
Free electrons tend to move through conductors with some degree of friction, or opposition to motion. This opposition to motion...

...New York City College of Technology
Ohm’s law & resistors in parallel & in series
Lab 4
Class: PHY 1434-E475
Due date: March, 13 20144
Group Names: Hisham Sageer
Objectives:
Our object is to confirm Ohm’s law by analyzing the dependence of the electrical current as a function of voltage and as a function of resistance. Also, we studied the current flow and voltage in series and parallel. Finally, the lab determined the equivalence resistance of series and parallel combination of resistors and compared the results with theoretical data.
Theoretical Background:
The first thing that needs to be described in this lab is what the electric current I:
I =. The electric current is defined as charge over time and the unit is ampere (A). In a case where we have the voltage, resistance and current we can set the equation for resistance to be; R = where the unit is called Ohm (Ω). “The current through a resistor is directly proportional to the applied voltage V and inversely proportional to the resistance” (College Physics Laboratory Experiments, 43) in our lab experiment we used some machinery to produce and to measure voltage and some current. We were then able to find its resistance. These apparatus are called ammeter which displays the amount of current in circuit, and the voltmeter to read the voltage (potential difference). Reminding that this diagram is named circuit and V is applied...

...Conclusion
Ohm's Law states that V=RI where V is the difference of potential at the poles of the element (measured in volts), R is the resistance of the element being tested (a resistor in this case, measured in ohms), and I is the current passing through the circuit (measured in milliamps). When the Y-intercept on the attached voltage drop vs. current in the conductor graph is examined, it is observed that the the ranges of R values overlap, also the expected y-intercept value of 0 falls between the maximum and minimum deviation. By further examining the graph,it is possible to notice that the plot of the voltage drop across the conductor versus the current in the conductor results in a straight line. Furthermore, the origin (0,0) is within experimental error for the y-intercept of the graph. Both these statements show that the tested resistor verified Ohm's Law since theoretically the y-intercept should be 0 and the voltage drop across the conductor versus the current in the conductor should be directy proportional. This can be concluded by observing the equation which is y = .054492x ± 0.0016x -.0254 ± 0.10.
This laboratory had few causes of error that could significantly affect results. The most important factor was a mildly fluctuating power supply (the indicated current did not remain perfectly stable after being adjusted). Another possible cause of error is the possibility of misreading the voltage drop because of the...

...Aim:
To determine the relationship between the length of eureka wire, and resistivity of the wire.
Hypothesis:
As the length of the wire increases, the resistance of the wire will increase.
Background:
Some materials have consistent resistance at the same temperature regardless of how much voltage is applied through them, these materials are known as ‘Ohmic’ resistors. This is because they are said to obey Ohm’s law, which states that if a voltmetre is used to measure the voltage (V) of an unknown resistance (R), and an ammetre is used to measure the current (i) through the same unknown resistance, then ‘R’ would be given by R = V/i . The eureka wire used in this experiment is an ohmic resistor, so theoretically it can be used to measure the relationship between its length and resistance without other variables affecting it.
Equipment:
1. 1 metre length of eureka wire
2. Power supply unit
3. 1 Voltmetre
4. 1 Ammetre
5. 1 Rheostat
6. Connecting wires
Procedure:
1. Measure and cut 1 metre of wire
2. Set up the electrical circuit as in the diagram
3. Set the rheostat at its furthest point on one end.
4. Connect the wire into the circuit at 10cm length
5. Turn the power supply on, and record the voltage and amp readings. Turn the power supply off immediately after to prevent temperature build up in the circuit.
6. Repeat step 5 twice, adjusting the rheostat to the middle position, and then the other end...