...------------------------------------------------- Ohm's law From Wikipedia, the free encyclopedia This article is about the law related to electricity. For other uses, see Ohm's acoustic law. V, I, and R, the parameters of Ohm's law. Ohm's law states that the current through a conductor between two points is directlyproportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance,[1] one arrives at the usual mathematical equation that describes this relationship:[2] where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.[3] The law was named after the German physicist Georg Ohm, who, in a treatise published in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire. He presented a slightly more complex equation than the one above (see History section below) to explain his experimental results. The above equation is the modern form of Ohm's law. In physics, the term Ohm's law is also used to refer to various generalizations of the law originally formulated by Ohm. The simplest example of this is: where J is the current density at a given location in a resistive material, E is the electric...
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...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, it...
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...¬¬¬¬¬¬Abstract Electrical circuits are described with mathematical expressions. Usually, it is possible to calculate the currents and voltages in a circuit by solving a set of equations, the calculations are required to design a safe circuit.and this is one reason why advanced mathematics is so important in the field of electrical engineering. The circuit equations can be determined using Ohm’s Law, which gives the relationship between voltage and current in a resistor (V=IR), and Kirchhoff’s Current and Voltage Laws, which govern the currents entering and exiting a circuit node and the sum of voltages around a circuit loop, respectively. Objective(s) The purpose of this experiment is to verify Ohm's Law using resistor in dc and ac circuits....
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...Network Modes Zachary Gurley NTC\405 August 10, 2015 Bradley Rush Network Modes Throughout time, Ethernet has transformed computer systems into a network of computing devices with unlimited potential. Before the days of Ethernet, networking was not very effective or efficient. The only way to transfer data before this time was to go from device to device and manually move files. Definitely not what I would call a good means of transporting data compared to the ways of today. However, during those times, you had to work with what you had. All of this was done before Ethernet was an industry standard. However, more recently, people have utilized the potential of Ethernet to move frames or packets across a network. Because of Ethernets adequate performance, and superior economics, it won the heart of network administrators and most people using networking equipment. Today, Ethernet focuses on wired LAN technology and continues to grow in speed and sophistication. Despite Ethernet’s sophistication, its means of communication is done in a systematic manner. For instance, Ethernet sends data across a network in frames or packets. Data is wrapped in six layers of assembly which consist of first a Preamble, next a recipient MAC address, followed by a senders MAC address, length, (Data), Pad, and the cyclic redundancy checker for errors of missed packets. Lastly, but more importantly, the foundation of Ethernet are found at the physical and data link layer of the OSI model...
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...Ethernet Ethernet Switching Modes Michael Martin NTC/405 February 16, 2015 Ronald Bowell Ethernet Switching Modes Ethernet has transformed computer systems from isolated, solitary islands to a network of computing devices with limitless potential. Unfortunately, before Ethernet, network computing was administered solely by proto-geeks who wore white coats and pocket protectors. Previously, the best idea these so-called geeks came up with before Ethernet, was sneaker-net, which meant individuals had to save the files to a disk, lace up their tennis shoes and marched to the next computing device. All of this was done before Ethernet was an industry standard. However, more recently, geeks have utilized the potential of Ethernet to move frames or packets across a network. Ethernet invented and utilized in the 1990s focuses on a hybrid star bus (Meyers, 2009). Because of Ethernets adequate performance, and superior economics, it won the heart of network administrators and most people using networking equipment. Today, Ethernet focuses on wired LAN technology and continues to grow in speed and sophistication. Despite Ethernet’s sophistication, its means of communication is done in a systematic manner. For instance, Ethernet sends data across a network in frames or packets. Data is wrapped in six layers of assembly which consist of first a Preamble, next a recipient MAC address, followed by a senders MAC address, length, (Data), Pad, and the cyclic redundancy checker...
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...OHM’s Law Although there are literally thousands of formulas, I only try to remember two: Ohm's Law and the Power Formula. You can deal with most anything built before 1980 (except radio and TV) with these two formulas. The first, Ohm's law, states that E = I x R (Or, electromotive force in volts = intensity in amps, times the resistance). So those of you that are good at math games already know that we can change it to read R = E/I or I = E/R. That first class back in the sixties taught it as a magic circle, with E over I x R and you just took the one you wanted to know out of the circle and did what was left . I.e. If you want to know amps, you take the I out which leaves E/R, so you divide the volts by the resistance to find the amps. The power formula states that P = E x I or Power (in Watts) = Volts times Amps. It can also be remembered as a magic circle.Simply plug the resistance that you measure in to Ohm's Law and solve. More on this later - I’m getting ahead of my self. You may see these written with different symbols, depending upon when a book was written, but this is the way it was taught when my Scout was new. We will get back to formulas later. Now I want to go into electricity’s alter ego. | Ohm's Law: E = I x RPower Formula: P = E x I Magic triangle or circle (click for full-size view with comments) | Magnetism is the force possessed by some materials which enables them to attract or repel certain other materials. Magnets fall into...
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...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 increases...
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...Activity 1.2.3 Electrical Circuits – Simulation Introduction Since the late 1800s, engineers have designed systems to utilize electrical energy due to its ability to be converted, stored, transmitted, and reconverted efficiently into other forms of energy. In the 21st century, electrical energy production, distribution, and application have become consumer driven. Today’s consumer utilizes electrical energy in all aspects of life, from cell phones and computers to refrigeration and heating and cooling systems, and even transportation. Electrical energy, depending on geographic location, is converted from mechanical energy, chemical energy, light energy, and thermo energy before it reaches the consumer. Regardless of the conversion process, electrical energy consists of three basic components: current, voltage, and resistance. Current is the net transfer of electric charge per unit of time. Voltage is the amount of work required to move a charge from one point to another. Resistance is the opposition to the flow of current. Understanding the relationship between current, voltage, and resistance allows engineers to design efficient, safe, and functional electrical circuits. Electrical circuits consist of the following components: an energy source to provide voltage, conductors to allow current travel, insulators to limit current travel, and a load. Electrical circuits provide an uninterrupted path for current travel and are broken into two distinct categories of design:...
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...Parallel resistor-capacitor circuits Using the same value components in our series example circuit, we will connect them in parallel and see what happens: (Figure below) Parallel R-C circuit. Because the power source has the same frequency as the series example circuit, and the resistor and capacitor both have the same values of resistance and capacitance, respectively, they must also have the same values of impedance. So, we can begin our analysis table with the same “given” values: This being a parallel circuit now, we know that voltage is shared equally by all components, so we can place the figure for total voltage (10 volts ∠ 0o) in all the columns: Now we can apply Ohm's Law (I=E/Z) vertically to two columns in the table, calculating current through the resistor and current through the capacitor: Just as with DC circuits, branch currents in a parallel AC circuit add up to form the total current (Kirchhoff's Current Law again): Finally, total impedance can be calculated by using Ohm's Law (Z=E/I) vertically in the “Total” column. As we saw in the AC inductance chapter, parallel impedance can also be calculated by using a reciprocal formula identical to that used in calculating parallel resistances. It is noteworthy to mention that this parallel impedance rule holds true regardless of the kind of impedances placed in parallel. In other words, it doesn't matter if we're calculating a circuit composed of parallel resistors, parallel inductors, parallel capacitors...
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...been able to pick up on it before reading the article, though I hadn’t. If you are measuring voltage drops on individual loads and thusly looking for an open circuit through current movement then that is fine. However you do have to remember that the voltage drop has to be an actual “drop” from the original power applied (12V ish). “Subtracting the value you see at the input from what you saw across the battery terminals will tell you how much of your source voltage has been dropped before whatever is left appears at the load input” (Glassford, p.4). That just confuses me, and makes me think that it is going to be a hard way to figure out something that I should just know how to do. The alternate way, and easier way is to put the voltmeter positive lead on the positive battery terminal and the negative lead on the input directly before the load you want to measure. In doing this you have cut out the actual math and made the meter do the math for you. This will tell you what the difference in voltage is between the two probes. If your meter leads are to short to do this, make a jumper wire, which is what I will be doing, to avoid the math. This “all inclusive” way to check for excessive voltage drops is a great tool, which I will remember now when looking for an open...
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...Name: Date: 13.3 Ohm's Law A German physicist, Georg S. Ohm, developed this mathematical relationship, which is present in most circuits. This relationship is known as Ohm's law. This relationship states that if the voltage (energy) in a circuit increases, so does the current (flow of charges). If the resistance increases, the current flow decreases. Voltage (volts) Current (amps) = --------------------------------------------Resistance (ohms, ) To work through this skill sheet, you will need the symbols used to depict circuits in diagrams. The symbols that are most commonly used for circuit diagrams are provided to the right. If a circuit contains more than one battery, the total voltage is the sum of the individual voltages. A circuit containing two 6 V batteries has a total voltage of 12 V. [Note: The batteries must be connected positive to negative for the voltages to add.] If a toaster produces 12 ohms of resistance in a 120-volt circuit, what is the amount of current in the circuit? Given The resistance (R) is 12 ohms. The voltage (V) is 120 volts. Looking for The amount of current (I) in the circuit. Relationships V I = -R Solution 120 volts I = V = --------------------- = 10 amps -R 12 ohms The current in the toaster circuit is 10 amps. If a problem asks you to calculate the voltage or resistance, you must rearrange the equation I=V/R to solve for V or R. All three forms of the equation are listed below. V V II = V-V IR R R R I In this section...
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...Section A: In Section A we once again like always used the Simpson VOM, as an ammeter measure and read current in the circuits give to us. Are group used the VPS meter to power the whole circuit to read are measurements. What we did is set the VPS to a given voltage that was required and had it connected to our resistor board with alligator clips to read different measures of current. Also a precaution we took was we made sure our values were set right, if not we could have damaged the components if not set correctly. We were given circuits that had voltage and ohm readings and used Ohm's law (V=I*R) to measure current. Also we used the Simpson as a visual check to make sure we were doing everything right. Section B: In Section B, we did kind of what we did in Section A. We constructed a series circuit by using our VPS, resistor board, and the Simpson VOM. Then we placed the negative and positive lead on the VOM into the circuit. We set the rage to 10mA, and the set the VPS to zero originally, then increased it to 6mA. When we were ready, we turned off the VOM and VPS and measured for every resistor values for the voltage and resistance that was required of us. After we measured all the values that was required, we also measured the percent difference of the measured value and the calculated value and got a percent value. The percent value determines if your calculations are on point....
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...arrangements. The second objective investigates how the voltage across the light bulb varies with the amount of current through it. Finally, the last objective is to explore how the length of a wire affects resistance. Procedure- Activity 1 A) Measure the voltage across an open-circuit cell by connecting the positive terminal of the voltmeter to the positive terminal of the call and the negative terminal of the voltmeter to the negative terminal. The voltage across cell #1 is 1.462 V. The voltage across cell #2 is 1.455 V. B) Measure the voltage across two cells connected in a series. The voltage across two cells is 2.9 V. C) Connect the circuit as shown in the diagram below. Insert two D-cells into the circuit. D) What is the effect of rotating the knob on the device that is identified as a “Potentiometer”? Rotating the potentiometer adjusted the brightness of the light bulb. Activity 2 A) Set the multimeter to the 200/400 mA range. Connect the circuit as the same in activity one with the ammeter in the circuit. Set the second multimeter to the VDC scale and connect its leads across the bulb. B) Read the current that is flowing through the bulb. Measure the voltage across the bulb. Record both values in the data table below. C) Turn the knob of the potentiometer and increase the current about 20 mA at a time. Measure and record the voltage and current each time. D) Remove the bulb from your circuit and replace it with a 10 Ω resistor...
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...Lesson 13g: Resistors in Series and Parallel Circuits Any path along which electrons can flow is a circuit. • For a continuous flow of electrons, there must be a complete circuit with no gaps. A • A gap is usually a switch that can be closed (on) to allow electron flow or open (off) to stop electron flow. • If I wanted to draw a schematic diagram (aka 9V circuit diagram) of a resistor powered by a battery that can be turned off and on, it might look like Illustration 1. ◦ Note that the placement of the switch (SW1) near the positive terminal (what we would consider the end of the electron flow path) does not matter. A switch anywhere in the circuit will have the same effect of stopping current flow. ◦ Switches are shown in the open (off) position so they are easier to spot in the diagram. In a closed (on) position, the current would be able to flow through the whole circuit. Illustration 1: A simple schematic diagram of a battery connected to a switch and resistor. Most circuits used in modern devices will have several components, hooked up in a variety of combinations. All of these circuits can be broken into two main categories, series and parallel. • In all circuits, going through a battery increases voltage, while going across a resistor decreases voltage (a voltage “drop”). • As you go around any single pathway the total voltage drops across all resistors must equal the voltage from the battery. Series Circuits In a series circuit there is only a single pathway for electron...
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...Electrochemical Analysis Introduction: In 1791 Luigi Galvanic discovered electrical activity in the nerves of the frogs that he was dissecting. He thought that electricity was of animal origin and could be found only in living tissues. A few years later, in 1800 Alessandro Volta discovered that electricity could be produced through inorganic means. In fact, by using small sheets of copper and zinc and cloth spacers soaked in an acid solution, he built a battery - the first apparatus capable of producing electricity. Naysayers were quick to predict that electricity would never serve a useful purpose. Obviously they were very wrong. Electricity has a central role in our lives and to this day Electrochemistry is a standard course of study. While listening to lessons on Electrochemistry, many students may wonder why it was ever invented, if it was really ever necessary to invent it and if the world would be better off without it. With the small experiments that follow, we hope to make peace between these students and the study of Electrochemistry. These fun and simple experiments can teach the fundamental concepts of Electrochemistry without asking much of the student. As you will see, many of these demonstrations are easily adapted to various configurations and each can be done independently or as part of the full curriculum. POROUS VASE - An actual porous vase made for the purpose may be difficult to acquire. It is used to prevent the quick mixing of various solutions, while...
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