...HOMEWORK PROBLEMS Chapter 27: CAPACITANCE AND DIELECTRICS Show the equations and calculations, and box your answer. Be sure to include the units. NOTE: Any four questions from this HW will be graded, and the marks for this HW will be based on these only. (1, 2, 3, 12, 13, 18, 19, 21, 22, 29, 31, 32, 44) 1. A proton beam in an accelerator carries a current of 125 A. If the beam is incident on a target, how many protons strike the target in a period of 23.0 s? 2. A copper wire has a circular cross section with a radius of 1.25 mm. (a) If the wire carries a current of 3.70 A, find the drift speed of the electrons in this wire. 3. An aluminum wire having a cross-sectional area equal to 4.00 10–6 m2 carries a current of 5.00 A. The density of aluminum is 2.70 g/cm3. Assume each aluminum atom supplies one conduction electron per atom. Find the drift speed of the electrons in the wire. 12. A lightbulb has a resistance of 240 when operating with a potential difference of 120 V across it. What is the current in the lightbulb? 13. An electric heater carries a current of 13.5 A when operating at a voltage of 120 V. What is the resistance of the heater? 18. Aluminum and copper wires of equal length are found to have the same resistance. What is the ratio of their radii? 19. If the magnitude of the drift velocity of free electrons in a copper wire is 7.84 10–4 m/s, what is the electric field in the conductor? 21. If a certain silver wire has a resistance...
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...Examination Questions Physics P2 part 1 Q1.(a) A driver on a motorway sees a hazard ahead and brakes to stop. The stopping distance of the car is the thinking distance added to the braking distance. (i) What is meant by: thinking distance ................................................................................... ............................................................................................................... braking distance .................................................................................... ............................................................................................................... (2) (ii) The graph shows how the velocity of the car changes during the stopping distance. Use the graph to determine the thinking distance and the braking distance. ............................................................................................................... ............................................................................................................... Thinking distance = ....................................... m Braking distance = ........................................ m (2) (b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe and explain the factors that affect the stopping distance of a vehicle. In your answer you should: • describe factors that affect...
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...change the future especially when it comes to transportation. The main idea of future of transportation is to reduce emissions and the amount of people in individual vehicles. A major concern is the use of our fossil fuels, and the damaging gasses that are released during the combustion of these fuels in our vehicles. Researchers for years have been coming up with ideas to reduce the carbon footprints of these things. Energy experts and historians of energy agree that as societies advance, they need more and more concentrated, intense forms of energy, like rocket fuel instead of gasoline. Transportation will be pollution-free and versatile. “of the several converging trends for getting around, “ultracapacitors” are being developed for electric cars to completely replace batteries. They have lighter weight and ten times the energy density of lead-acid batteries. In the future energy portfolio, another surprising development is the permanent magnet powered motors, which are an emerging trend bound to come to market. A number of developments, such as the Spiral Wankel Magnetic Motor and other different designs, all point to the use of the “magnetic gradient” in the...
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...laws or more specifically Kirchhoff Current and Voltage laws. These laws are very helpful in determining the equivalent electrical resistance or impedance of a complex network and the currents flowing in the various branches of the network. These laws are first derived by Guatov Robert Kirchhoff and hence these laws are also referred as Kirchhoff Laws. We saw in the Resistors tutorial that a single equivalent resistance, ( RT ) can be found when two or more resistors are connected together in either series, parallel or combinations of both, and that these circuits obey Ohm’s Law. Sometimes in complex circuits such as bridge or T networks, we cannot simply use Ohm’s Law alone to find the voltages or currents circulating within the circuit. For these types of calculations we need certain rules which allow us to obtain the circuit equations and for this we can use Kirchhoff’s Circuit Law. These two rules are commonly known as: Kirchhoff’s Circuit Laws with one of Kirchhoff’s laws dealing with the current flowing around a closed circuit, Kirchhoff’s Current Law, (KCL) while the other law deals with the voltage sources present in a closed circuit, Kirchhoff’s Voltage Law, (KVL). Kirchhoff’s Current Law is the 3 currents entering the node, I1, I2, I3 are all positive in value and the 2 currents leaving the node, I4 and I5 are negative in value. The term Node in an electrical circuit generally refers to a connection or junction of two or more current carrying paths or elements such...
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...Prof. Pascia Pceit-17-101P Electromagnetic Induction Michael Faraday formulated that electromotive force (EMF) produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electric current will be induced in any closed circuit when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. In mathematical form, Faraday's law states that: where is the electromotive force ΦB is the magnetic flux. For the special case of a coil of wire, composed of N loops with the same area, the equation becomes A corollary of Faraday's Law, together with Ampère's law and Ohm's law is Lenz's law: The EMF induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in magnetic flux which produces the EMF Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids.[1] Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829.[2] Around 1830[3] to 1832[4] Joseph Henry made a similar discovery, but did not publish...
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...does not allow electrons to pass 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...
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...Names: Shaira Eden B. Laranjo Aljay Saren Date: August 09, 2013 Subject: Physics Discipline: Electricity and Magnetism TITLE The Effects of Powering household or any Low Amperage devices using Acetic Acid battery. OVERVIEW Worldwide: Electricity and Magnetism are the important part of the life in many parts of the world. You’re likely to use electricity every day, without even thinking about it. Electricity and Magnetism are involved. How electromagnetism changed our World? Electromagnetism has created a revolution not only in the field of engineering, but also in various other fields like medicine, space, construction etc. Electromagnetism affects our World in million ways. Whatever powered devices we use, from table clocks to microwave ovens, from useful appliances to high-technology materials, and other relevant devices in order to communicate have some of electromagnetic principle involved in their functioning. Thus it is evident that the usage of electromagnetism is wide and everywhere. Everyday more and more equipments take birth in the market due to the development in magnetism and electromagnetic studies. Few decades ago, only few places on our planet Earth had the facility to enjoy the electricity and electronic devices. But recent developments led to fast track life style and rapid competitive improvement in every field competing with every country. With the introduction of electricity and electrical devices, electronic devices,...
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...treatments that use electrical currents passed through the skin to produce many therapeutic effects. In this report I have researched and written about nine machines and the effects they have on the body. High Frequency. The high frequency machines can be a small table top unit or a large free standing unit, with many of the larger units housing a number of different electrical equipment. Most units have two switches: one on/off and the other to control intensity. Once the unit is switched on it produces an electrical impulse which passes through an electrode that delivers a current to the client. There are several electrodes which fit into the handle that is attached to the machine via a lead. Each electrode is made of glass, normally with a metal end which is pushed into the handle. The electrode has a small amount of either air, neon, or mercury sealed within. Once the machine is switched on the current flows from the unit to the handle and connects to the electrode via the metal end. The air or gas within the electrode becomes ionised and is dispersed into the tissue area. The electrode will glow: Violet-Air Orange-Neon Blue violet-Mercury There are two methods of application direct and indirect. Each using different electrodes for different effects. The electrode used within the indirect method is the saturator which is placed in the handle of the unit. The client holds the handle in one hand whilst the saturator is in the other. Current passes through the handle into...
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...Troubleshooting Electrical Circuits EET-110 Research Paper Prof. Jeevan D’Souza I pledge to support the Honor System of ECPI. I will refrain from any form of academic dishonesty or deception, such as cheating or plagiarism. I am aware that as a member of an academic community it is my responsibility to turn in all suspected violators of the honor code. I understand that any failure on my part to support the Honor System will be turned over to a Judicial Review Board for determination. I will report to a Judicial Review Board hearing if summoned. Signature: Gary Martin- 1/17/2016 Narrative My Topic for this research paper is Troubleshooting Electrical Circuits. I have a little experience with troubleshooting and maintenance of electrical circuits. I used to work in maintenance for a gentleman that owned twelve Burger Kings in my area. It was a very busy job, especially with regards to electrical issues. These Burger Kings had a lot of equipment, signs and electronics that required electrical power. Most of the equipment required extreme heat and for extended periods of time. When I started the job, I would go into one of my BK’s and the first thing I would do with an electrical issue was to test the issue to see what results I might get, most of the time the equipment just didn’t work at all. I would then go turn off the power to the equipment but, first I would make sure the breaker wasn’t thrown and the equipment had been properly plugged in to the power outlet...
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... To calibrate a one meter slide wire potentiometer using a standard cell and then to use this potentiometer to measure the emf of a test cell. The terminal voltage of the same test cell is then measured as different load resistors are connected across the test cell and these data are used to determine the internal resistance of the test cell. THEORY The electromotive force (emf) of a cell is its terminal voltage when no current is flowing through it. The terminal voltage of a cell is the potential difference between its electrodes. A voltmeter cannot be used to measure the emf of a cell because a voltmeter draws some current from the cell. To measure a cell's emf a potentiometer is used since in a potentiometer measurement no current is flowing. It employs a null method of measuring potential difference, so that when a balance is reached and the reading is being taken, no current is drawn from the source to be measured. Figure 1. This is the basic circuit diagram for a potentiometer. Point C is the sliding contact which can be adjusted for zero current deflection through the galvanometer. In this method (refer to Figure 1) a uniform, bare slide wire AB is connected across the power supply. If you were to connect a voltmeter between the + power supply terminal and point A you would measure essentially zero volts. If you were to now connect the voltmeter between the + power supply and point B you would measure a voltage equal to the terminal voltage of the power supply which...
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...LESSON 1: History of Electronics The introduction of vacuum tubes at the beginning of the 20th century was the starting point of the rapid growth of modern electronics. With the vacuum tubes the manipulation signals became possible, which could not be done with the early telegraph and telephone circuit or with the early transmitters using high voltage sparks to create radio waves. Example: weak radio and audio signals can be amplified, audio signals such as music or voice can be superimposed radio waves. The development of a large variety of tubes designed for specialized functions made possible the swift progress of radio communication technology before World War II and the development of early computers during and shortly after the war. The transistor invented in 1948, has now completely replaced the vacuum tubes in most of its application. Incorporating an arrangement of semiconductor materials and electrical contacts, the transistor provides the same functions at reduced cost, weight and power consumption and with higher reliability. Subsequent advances in semiconductor technology, in part attributable to the intensity of research associated with the space exploration effort led to the development of the integrated circuit. Integrated circuits may contain hundreds of thousands of transistors on small piece of material and allow the construction of complex electronic circuits, such as those in microcomputers, audio, and video equipment and communication satellites. ...
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...Militaries, security agencies, and even government agencies will all benefit a great deal from new transport systems that earmark the future due to revolutionary knowledge of transportation and technology. With all the advancements in technology over the years, we have seen an increase in the use of electricity and magnetism being used in the transportation industry. As of now there are several types of electric cars out there that are being used. But as technology advances and we look into the future of transportation we will begin to see many more forms of transportations that use the power of electricity and magnetism to increase the efficiency of traveling around your city or even around the world. For many years now scientists have been working on trying to perfect the technology needed for electric cars. Electric cars, as the name suggests, use electricity to the motor of the car to make it run. Electric cars are considered to be three times more efficient than cars with the normal internal combustion engine, but there are even more advancements in the electric car...
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...EXPERIMENT 9: KIRCHOFF’S RULES Introduction Kirchhoff’s Law is defined through two separate components which are Kirchhoff’s Current Law and Kirchhoff’s Voltage Law. These two laws are collinearly related through its total summation being which is equal to 0, except that for Kirchhoff’s Current Law having its variables to be of currents flowing into and outward a node (fig.1), and for Kirchhoff’s Voltage Law having its variables in terms of the drops and rises of its voltages in a closed loop (fig. 2). ∑▒I_in +∑▒I_out =0 Figure 1: Kirchhoff’s Current Law ∑▒V=0 Figure 2: Kirchhoff’s Voltage Law For experiment 9 entitled Kirchhoff’s Rules, the activity hoped to exemplify and prove Kirchhoff’s Law in mainly one aspect of his law which...
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...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 does make sense according to the formula (V=IR). In question 2 where the voltage was set at 6V, the current was higher when the resistance was 100 ohms than when the...
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...[Your First Name Your Last Name] [Teacher’s Name] [Class Name/Period] [Date (January 26, 2015)] Resistance and Resistivity Resistance is the property of a substance which makes it oppose the flow of an electric current through it. Generally, metals acids and liquid salts and salt solutions are very good conductors of electricity. Metals with higher numbers of delocalized electrons have higher conductivities than those with fewer delocalized electrons. For example, aluminium is more conductive than copper which is also more conductive than copper. When an electric current is applied to a conductor, the delocalized electrons assume a directed motion depending on the polarity of the potential difference. As the electrons move, they collide and bombard with atoms and molecules of the conducting material, thereby creating heat (T. B. Theraja). Materials which offer higher hindrance to the flow of electrons on application of a potential difference are called poor conductors of electricity. Examples of poor conductors are: Polyvinyl chloride (PVC), dry wood, rubber, glass and mica. Insulators are used in the coating of conductors to prevent electrical shocks .Resistance is measured in ohms denoted Ω. Depending on the degree of resistances other commonly used units are; mega-ohms (M Ω), kilo-ohms (k Ω), mill-ohms (m Ω) and micro-ohms (μ Ω) (T. B. Theraja). Resistance of a material is derived from the factors affecting it. According to the laws of resistance, resistance is directly...
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