In: Science

Submitted By cmwalker545

Words 359

Pages 2

Words 359

Pages 2

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) Stays the same.

Procedure Part II: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law mA is milliamps, and 1000 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.

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 |0.01 A |800 Ω |

|2.0 V |.044 A | 50 Ω |

| 2.5V |.0058 A |430 Ω |

| 6.9 V |.069 A |100 Ω |

|6.4 V | 0.0213A |300 Ω |

Conclusion Questions: ( ½ pt each)

1. Incandescent light bulbs have a very thin filament that glows when hot. Thin filaments have very low resistance.

2. The 12V battery in your car operates a 25 amp car stereo. What is the resistance of this stereo system? 0.48 ohm

3. A “2D” Maglite flashlight runs on 3.0V. What is the current through the bulb if resistance is 15 Ω ? .20 amps

4. How many volts must an iPod charger provide to charge an iPOD using .85 Amps at 35 Ω? 29.75 V

5. You need to buy a long extension cord to power a stereo at your spring break BBQ. You need 200feet. You have a 50 ft cord that will work.…...

...metal wire, together with the physical dimensions of the wire, from which you will calculate the resistivity of the metal. Theory The resistance R of a component in a circuit is given by the equation V = IR where V is the potential difference across the component and I is the current in the component. The resistance of a wire is given by the equation R = ρl / A where ρ is the resistivity of the metal from which the wire is made, l is the length of the wire and A is its cross-sectional area. Using the circuit below, you will make measurements of current and voltage for different lengths of wire. You will plot a graph of resistance against length and from this you will calculate the resistivity. A V flying lead zero end of the metre rule tape to hold wire into place resistance wire 70 © University of Cambridge International Examinations 2006 Teaching AS Physics Practical Skills Resistivity of a wire Student Worksheet Making measurements and observations Use the micrometer screw gauge to measure the diameter d of the resistance wire in several places along the length. Each time you take a measurement at a new place, rotate the wire slightly. 1 Tape the wire to the metre rule so it cannot slip and the markings of the rule are visible. 2 Connect the circuit shown in the diagram above. The flying lead should have a bare conducting end and should be long enough to touch any part of the resistance......

Words: 802 - Pages: 4

...Purpose: The purpose of this lab is to determine the relationship between current (dependent variable), voltage (independent variable), and resistance and to compare the voltage vs current behavior of a resistor to that of a lightbulb Apparatus: LabQuest LabQuest App Vernier Current Probe Vernier Differential Voltage Probe Wires Clips to hold wires Light bulb (6.3 V) Adjustable 5 volt DC power Supply 2 resistors (10 and 51 Ohm) Procedure: 1. Connect the Current Probe and Differential Voltage Probe to LabQuest and choose New from the File menu 2. Connect the power supply, 10 Ohm resistor, wires, and clips as shown in the diagram. 3. Zero both probes with no current flowing 4. Using the 10 Ohm resistor, find the value of the current that flows in the circuit for various values of the potential. Start with 0 volts, increasing by .5 volts each time; record in a data table. 5. Repeat with the lightbulb and the 51 Ohm resistor Data: 10 Ohm Resistor: Voltage (watts) | Current (amperes) | 0 | 0 | .533 | .0551 | .880 | .0911 | 1.692 | .1752 | 2.735 | .2833 | 3.188 | .3303 | 4.642 | .418 | 51 Ohm Resistor Voltage (watts) | Current (amperes) | 0 | 0 | .513 | .0101 | 1.007 | .0201 | 1.969 | .0398 | 2.940 | .0595 | 3.904 | .0795 | 4.905 | .0997 | Lightbulb Voltage (watts) | Current (amperes) | 0 | 0 | .264 | .0472 | .362 | .0570 | .480 | .0570 | .532 | .0564 | .734 | .0648 | .958 | .0746 | 1...

Words: 1065 - Pages: 5

...Michelle Cameron-Bex Greg Berry Writing227 July 9, 2013 Ohm’s Law What is Ohm’s Law? Ohm’s Law is a law relating the voltage difference between two points, the electric current flowing between them, and the resistance of the path of the current. Mathematically, the law states that V = IR, where V is the voltage difference, I is the current in amperes, and R is the resistance in ohms. For a given voltage, higher resistance entails lower current flow. Where did it originate from? Ohm's Law comes from Georg Simon Ohm who was born in Bavaria in 1789. His father taught him philosophy, chemistry, mathematics and physics. In 1806 Ohm became a mathematics teacher in Switzerland. In 1811, Ohm received a doctorate from Erlangen and then became a mathematics lecturer. In 1820, he learned of Oersted's electromagnetism discovery, began experimenting with electricity, and convinced himself of what is now known as Ohm's law. In 1825, he published a paper that explains the decrease in electromagnetic force (The fundamental force associated with electric and magnetic fields), which is proportional to current, around a wire as its length is increased. He published two papers in 1826 that mathematically describe electrical conduction in circuits. In 1827 he published his famous book Die Galvanische Kette, mathematisch bearbeitet, which contains what we now know as Ohm's law. How is it used? Ohm's Law can be used to solve simple electrical circuits. A complete circuit is one......

Words: 749 - Pages: 3

...In this investigation I am going to investigate what affect the resistance of a wire. Electricity flows in metals. Metal wires are made of millions of tiny metal crystals. Each crystal’s atoms are arranged in a regular pattern. The metal is full of ‘free’ electrons that do not stick to any particular atom. They fill the space between atoms in a metal. When these electrons move they create an electric current. Conductors have resistance, but some are worse than others. The free electrons keep bumping into atoms. A wires resistance depends on four main factors which are: Resistivity The length of the wire Cross sectional area The temperature of the wire I am going to investigate how the length of the wire affects the resistance. I have done a preliminary experiment to help me decide the best way to do my investigation. The results should also help me make a prediction. Preliminary Investigation Below are my results from the preliminary experiment (see table 1). I have taken three readings each from the Volts and current to make sure it is as accurate as possible Table 1 From the results I can see that as the length of the wire increases, the resistance increases as well. Furthermore I have noticed that if you double the length of the wire, the resistance is roughly doubled. E.g. when the length of the wire is 20cm the resistance is 3.14 ohms, when the length of the wire is 40cm the resistance is 6.18 ohms which is roughly double 3.14 ohms. In my main......

Words: 1588 - Pages: 7

...Year 11 Physics Investigation- What factors affect the resistance of a wire? Introduction We are trying to find out if the thickness of a wire affects the resistance of a wire and also how it will do that. One reason I chose this investigation was because human reaction time is eliminated by not using the parachute method (the parachute experiment is to find out the factors affecting the rate of decent of a parachute), because you have to measure the timings on it by the eye and hand pressing the stop button and there could be some inaccuracies in this. In the test I am doing there is no space for human error because all the measuring is done by equipment and machines so all I have to do is make sure I use them properly and read them with accuracy. The wire resistance experiment is more precise because the equipment I will use to measure all sorts of different factors in the experiment is more precise than in the parachute experiment mainly because everything is still and not moving in the resistance experiment. We have chosen to do the thickness of the wire because it is easy to control and keep accurate because of the micrometer, which is very precise. In the parachute investigation I would have to measure the distances with a ruler and the micrometers precision is 0.01mm which is a very high precision whereas the ruler has a lower precision of 1mm. We could have used the material as a variable but when we get a graph of results it will be a bar......

Words: 1998 - Pages: 8

...through is an insulator. Conductors intended to have resistance are called resistors (symbol ) Voltage- given the symbol V, measured in volts using a voltmeter Current- given the symbol I, measured in Amperes using an ammeter Metallic structure diagram Resistance Resistance is the ability to prevent or resist the flow of electrical current. Resistance occurs in an electrical circuit because of a collision between electrons and atoms, which slows the electrons down and converts some of their KE to heat energy. Resistance is measured in Ohms (Ω). Diagram Arrow shows direction of electron movement through the wire. Equation [pic] Factors which affect resistance Length of wire – this is being investigated Thickness of a wire – in a thin wire there are more possible paths for the electrons to pass through, therefore more electrons can flow through at one time, this increases the current which increases the resistance. Material of wire - wires of different densities will block more or less electrons Temperature - the vibration of warm molecules makes them more likely to collide with electrons, and resistance increases with temperature. Variables Independent- length Dependent - Voltage, current to measure, resistance Controlled - Temperature, material of wire, cross sectional area Circuit diagram Method 1. set up apparatus as shown above 2. measure out a 1m length piece of wire and connect it to the crocodile......

Words: 927 - Pages: 4

...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______. 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 |.0213A |300 Ω | Conclusion Questions: ( ½ pt each) 1. Incandescent light bulbs have a very thin......

Words: 339 - Pages: 2

...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 100) 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 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 |0.01 A |800 Ω | |2.0 V |.044 A |45.5 Ω | |2.5 V |.0058 A |430 Ω | |6.9 V |.069 A |100 Ω | |6.4 V |0.0213 A |300 Ω | Conclusion Questions: ( ½ pt each) 1. Incandescent light bulbs have a very thin filament that glows......

Words: 388 - Pages: 2

...ChCharles’ Law: The Effect of Tempeture on Volume I.)Purpose: The purpose of this lab is to determine the effect of tempeture on the volume of a gas when pressure is constant and to use the volume and tempeture data to calculate a constant K, showing the relationship between these values. II.)Materials: 250 mL Erlenmeyer flask, No. 6 one hole rubbber stopper, 600 mL beaker, graduated cylinder, large pneumatic trough, glass tubing, laboratory burner, ring stand, ring, wire gauze, and buret clamp III.)Procedure: First, set up the apparatus in Figure 27-1. Next, obtain a 600 mL beaker and add approximately 250 mL of tap water. Then, obtain a 250 mL Erlenmeyer flask. Place a one-hole stopper fitted with a 3 cm glass tube or a dropper pipet in the flask and place the flask in the beaker of water. Heat the water to it’s boiling point and record the tempeture as T1. Continue heating at this tempeture for 3-5 minutes. Next, prepare a pneumatic trough or stopper the sink and add water. Remove the flask from the beaker and protect your hand with a towel while placing your finger firmly over the end of the glass tubing. Then remove your finger from the glass tubing and hold the flask under water ubntil the flask has cooled and the water ceases to enter. Raise the flask until the water levl inside is equal to the water level outside. Place your finger over the glass tubing while the outside and inside levels are equal. Remove the flask and place it in an upright position on your lab......

Words: 436 - Pages: 2

...Name: _Amogh Prabhakar____________ Date: Oct. 10, 2014___ CP: _____ Virtual Circuit Lab Learning Goals: Students will be able to understand Ohm’s Law. Students will be able to see the relationship between voltage, current, and resistance. Go to ⎝Battery-Resistor Circuit. Click on the green “Run Now” button. The simulation should look like the picture to the right. 1. Change the resistance and voltage. Observe what happens to the current. Note the relationship you observed between each of the following: (direct, inverse, none) a. resistance and current = _indirect_______________________ b. voltage and current = direct__________________________ Go to ⎝Ohm's Law. Click on the green “Run Now” button. The simulation should look like the picture to the right. 2. What is the current through a resistor with the following resistances? Let voltage = 6 V a. R = 100 ohms I = _60__ mA(current) b. R = 300 ohms I = 20____mA(current) 3. Now, determine the current through the wire with the following volts. Let resistance = 500 ohms a. Volts = 3 V I = 6___mA(current) b. Volts = 6V I = 12____mA(current) 4. Think about the formula (V=IR), does this make sense according to this formula? Explain! (Be sure to include the relationship between resistance and current, and the relationship between voltage and current in your answer) Yes,......

Words: 932 - Pages: 4

...length of the wire affects the wires resistance. Also measuring the voltage and current. A thin and a thick wire are used to get the results needed. There are three factors that influence the resistance of w wire which are, the thickness of a wire, temperature and length. Knowing those factors and measuring them will show how the experiment went. Introduction: ------------------------------------------------- The resistance of a material is the extent to which is oppose the flow of current. “Electronics for today or tomorrow, 2nd Edition, Tom Duncan, page 8” Where as conductors have low resistance and inductors have high resistance. Further more resistance is measures with ohms. The main concept of the experiment is to investigate the difference in the resistance when having several lengths of a wire. The reason why different lengths of a wire affect the resistance is because the length of the will is increased which will also make the resistance increase as well, therefore electrons will have a longer distance to travel. Because of this the length of a wire should be proportional to the resistance. Conductors are good metals of electricity because they have low resistance which is why electrons get away easily just by applying the voltage. Furthermore, the resistance of a wire and the length of the wire both increase but the thickness of the wire decreases at the same time. Moreover, thin wires have high resistance but thick wires have low resistance. Due to Ohm’s law......

Words: 589 - Pages: 3

...Name ____________________ AP Physics Batteries, Resistance and Current (Giancoli CH 18) Prelab: 1. Batteries are made by the difference in the electronegativity of different metals. Electrons can flow spontaneously between metals that give off electrons easier to metals that are less likely to give off electrons. There is a substance between these metals that allow charge to flow (salt bridge) so net charge doesn’t build up and “turn off” the battery. Draw a diagram (use your text) of an alkaline battery showing the + terminal, - terminal (and the type of metals used), the direction of current (+) flow and what’s inside. 2. What is the resistivity (ρ) of a resistor? What characteristics of a resistor affect the resistivity? Write a formula for this relationship, label each variable and indicate the units used to measure each. Would resistivity be constant for a specific resistor? 3. What is the difference between resistivity (ρ) and resistance (R)? What are the units of each? Lab Activity: Log on and go to the PhET website (PhET.colorado.edu) Go to simulations, then “electricity” then to the following: “Battery-Resistor”: Check “show battery” and “show cores”, watch what happens, adjust some variables 1. Why do electrons (blue dots) move? Draw a diagram of the battery, label the flow of electrons. The flow of current (+) is opposite; draw this and note if toward or away from + terminal of the......

Words: 546 - Pages: 3

...between current and voltage for the resistor, as expected. Our experimental error for the factory versus actual resistance was only 4.77%. The resistance of the light bulb is not as linear as with the resistor. This is because the resistance changes when the light come on, as some of the energy is converted to heat in the filament. The critical point when the light first turns on is at O.456 Volts and you can see on the graph that the resistance begins to level off at this point. You can see the same point on the graph of current versus resistance because the line begins to curve at the corresponding critical point of 0.390 Amps. As the light gets brighter, more energy is lost as heat and the curve levels off even more. Conclusion: In the lab we measured resistance in a resistor and in a light bulb. We built a circuit and used an ammeter and a voltmeter to measure the current and the electric potential difference to measure resistance. The resistor has a linear relationship between current and resistance because resistance does not change as the current increases. However the light bulb is not linear because some energy is lost as heat in the filament when the light bulb comes on. Our experimental data confirms these hypotheses and you can see the point where the light bulb comes on and the line starts to curve on our graph. Lab Questions: 1. Electric resistance in materials is caused by energy being lost to heat when there are collisions with free electrons and atoms.......

Words: 420 - Pages: 2

...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. Additional Material Needed: Clean Drinking Straw Procedure Part I Wire Resistance: • Blow through the drinking straw. • Cut the drinking straw in half and blow through a half-straw. • Describe the effect of length on ease to blow air through the straw. There is more resistance when the straw is longer. • Cut the halves again in half. • With the four pieces, blow through one, then blow through all four made into a larger, square-shaped straw. • Describe the effect of straw size (diameter) on ease to blow air through the straw. Less resistance • Now, open the PhET Simulation Electricity, Magnets, and Circuits ( Resistance in a Wire[pic] As wire length (cm) increases, the resistance (Ω) INCREASES As wire area (cm2) increases, the resistance (Ω) DECREASES As wire density (Ωcm) increases, the resistance (Ω) STAYS THE SAME Procedure Part II: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law [pic] mA is milliamps, and 1000 milliamps equals one Ampere. • Move the potential (volts) and resistance (ohms) sliders and observe the current (amps) As voltage......

Words: 473 - Pages: 2

...PHYS 1112/2212 spring 2016 LAB #9 Batteries, Resistance and Current Introduction: Voltage can be thought of as the pressure pushing charges along a conductor, while the electrical resistance of a conductor is a measure of how difficult it is to push the charges along. Using the flow analogy, electrical resistance is similar to friction. For water flowing through a pipe, a long narrow pipe provides more resistance to the flow than does a short fat pipe. The same applies for flowing currents: long thin wires provide more resistance than do short thick wires. The resistance (R) of a material depends on its length, cross-sectional area, and the resistivity (the Greek letter rho), a number that depends on the material. The resistivity and conductivity are inversely related. Good conductors have low resistivity, while poor conductors (insulators) have resistivity’s that can be 20 orders of magnitude larger. Resistance also depends on temperature, usually increasing as the temperature increases. For reasonably small changes in temperature, the change in resistivity, and therefore the change in resistance, is proportional to the temperature change. Prelab: 1. Batteries are made by the difference in the electronegativity of different metals. Electrons can flow spontaneously between metals that give off electrons easier to metals that are less likely to give off electrons. There is a substance between these metals that allow charge to flow (salt bridge) so net charge......

Words: 749 - Pages: 3