...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 wire. 3 Using the flying lead, make a contact with the resistance wire so that a length...
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...Properties and typical application of a solid electrical conductor Copper Introduction: There are many good solid electrical conductors. Namely one main good solid electrical conductor is copper. As a technician (referring to the scenario given) I advise the use of copper as a solid electrical conductor and the reason will be explained below. Copper comes with many important properties conductivity, tensile strength and resistivity. The Cu represents copper in the periodic table and the atomic number which copper has Is 29. Applications of copper Applications of copper: nowadays copper is heavily used in...
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...Chapter 25 – Current, Resistance and Electromotive Force - Current - Resistivity - Resistance - Electromotive Force and Circuits Current Electric current: charges in motion from one region to another. Electric circuit: conducting path that forms a closed loop in which charges move. In these circuits, energy is conveyed from one place to another. Electrostatics: E = 0 within a conductor _ Current (I) = 0, but not all charges are at rest, free electrons can move (v ~ 106 m/s). Electrons are attracted to + ions in material _ do not escape. Electron motion is random _ no net charge flow Non-electrostatic: E ≠ 0 inside conductor _ F = q E Charged particle moving in vacuum _ steady acceleration // F Charged particle moving in a conductor _ collisions with “nearly” stationary massive ions in material change random motion of charged particles. Due to E, superposition of random motion of charge + slow net motion (drift) of charged particles as a group in direction of F = q E _ net current in conductor. Drift velocity (vd) = 10-4 m/s (slow) Direction of current flow: - In the absence of an external field, electrons move randomly in a conductor. If a field exists near the conductor, its force on the electron imposes a drift. - E does work on moving charges _ transfer of KE to the conductor through collisions with ions _ increase in vibrational energy of ions _ increase T. - Much of W done by E goes into heating the conductor, not into accelerating charges...
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...energy. * If no internal energy losses occurs in the battery then the potential difference between its terminals is called the ELECTROMOTIVE FORCE (emf) of the battery. * The unit for emf is the same as the unit for potential difference, the VOLT. * RESISTANCE * The resistance of wire or other object is a measure of the potential difference that must be impressed across the object to cause a current of one ampere to flow through it. * R = V/I * The unit of resistance is OHMS (Ω), 1Ω = 1V/A. * OHM’s LAW * Ohm’s Law originally contained two parts. * The defining equation for resistance, V = IR, also stated the R is a constant independent of V and I. * The relation V = IR can be applied to any resistor, where V is the potential difference between the two ends of the resistor, I is the current through the resistor, and R is the resistance of the resistor under those conditions. * GEORG SIMON OHM * 1787-1854 * A high school teacher in Cologne and later a professor at Munich * Formulated the concept of resistance and discovered the proportionalities expressed in * MEASUREMENT OF RESISTANCE BY AMMETER AND VOLTMETER * A series circuit consisting of the resistance to be measured, an ammeter, and a battery is used. * The current is measured by the ammeter. * The potential difference...
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...IB Higher Physics Internal Assessment Candidate Name: Aleksei Kuryla Candidate Number: Title: resistivity of nichrome |D |DCP |CE | | | | | DATA COLLECTION AND PROCESSING | |Criteria |( |Mark |Comments | |Aspect 1 |Raw results only shown | | | | | |Correct units | | | | | |Uncertainties shown | | | | | |Uncertainties justified | | | | | |Uncertainties to 1 sig fig | | | | | |Decimal places consistent with uncertainty | | | | |Aspect 2 |Processed...
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...REPORT Wheatstone Bridge and Resistance The 19th century was as very good era of discovery in electrical knowledge, and technology that laid the foundation for what we see today in our society. Scientist like Luigi Galvani for his work with frogs led to his discovery in 1781 of galvanic or voltaic electricity. Galvani found he could make the muscles of a dead frog twitch when he touched them with different metals or the current from a nearby static electric generator. Alessondra Volta for creating the first battery laid the foundation for many other great discoveries in this field. Some other great concepts that came later in 19th century was Ohms law, Electromagnetism, Faraday law, and many more. A discovery of great significant was done by Samule Hunter Chrisite in 1833 and improved by Charles Wheatstone in 1843. This discovery used a device know as a wheat stone bridge, which gives a precise method to measure resistance against a known standard. In the Wheatstone a comparative device measures two additional relative resistance from two separate resistors. The relative resistance equals the lengths of a divided wire wound in a coil of ten-turns within a potentiometer, a device allowing the manipulation of this resistant ratio. The goal of the this lab is to accurately use the methods created by the inventors by simulating their method in discovering this new phenomenon . In the lab we measured the electrical resistance using Wheatstone bridge, which was...
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...3.1 Project methodology Bonding of permanent join of metallic parts to form an electrically conductive path that ensures electrical continuity and capacity to conduct safe current. Grounding is vital to connect the metallic parts of an electrical appliances to the earth (ground) by using thick conductor wire with very low resistance for safety purposes. In other word, grounding is a connection of the neutral point of a power supply system to the earth to avoid danger during discharge of electric energy. Hazards that may occur due to failure of earthing system are electrocution, fire or explosion due to the leakage of current through undesired path and to ensure potential current carried by conductor does not rise with respect to the earth...
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...Physics EEI Contents Introduction 4 Astable Multivibrators 4 Overview of the 555 Timer 5 Integrated Circuit 5 Semiconductor material 7 Current and Resistance 9 Potentiometer 10 Calculation of the Voltages 11 Transistors 11 Light Emitting Diode (LED) 14 Capacitance 14 555 Timer Operations 15 Operation in the Astable State 17 Aim, Hypothesis, and Calculations 18 Aim 18 Hypothesis 19 Materials 20 Method 20 Variables 21 Independent variable 21 Dependant variable 22 Controlled variable 22 Results 23 Table 1: Theoretical Values of varying Resistor R1 23 Table 2: Experimental values varying resistor 1 (R1) 24 Table 3: Theoretical values varying resistor 2 (R2) 25 Table 4: Experimental values varying resistor 2 (R2) 26 Data Analysis and Discussion of Trends Using Appropriate Pot 1 27 Trend 27 Matching the Frequencies of the Chosen Songs 29 Overall Results 30 Discussion 31 Conclusion 38 References 40 Appendix 43 Error Calculations 43 The extra resistor from the wires connecting the components in the circuit 43 The effect of temperature on the resistivity of the fixed resistors in the circuit 43 Calculations of best pot 44 Choice of Resistor and Pot 44 Calculation of Frequency Ranges 44 Introduction Shaping and generation of waves is done using electronic circuits known as multivibrators. These circuits produce...
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...Physics EEI Contents Introduction 4 Astable Multivibrators 4 Overview of the 555 Timer 5 Integrated Circuit 5 Semiconductor material 7 Current and Resistance 9 Potentiometer 10 Calculation of the Voltages 11 Transistors 11 Light Emitting Diode (LED) 14 Capacitance 14 555 Timer Operations 15 Operation in the Astable State 17 Aim, Hypothesis, and Calculations 18 Aim 18 Hypothesis 19 Materials 20 Method 20 Variables 21 Independent variable 21 Dependant variable 22 Controlled variable 22 Results 23 Table 1: Theoretical Values of varying Resistor R1 23 Table 2: Experimental values varying resistor 1 (R1) 24 Table 3: Theoretical values varying resistor 2 (R2) 25 Table 4: Experimental values varying resistor 2 (R2) 26 Data Analysis and Discussion of Trends Using Appropriate Pot 1 27 Trend 27 Matching the Frequencies of the Chosen Songs 29 Overall Results 30 Discussion 31 Conclusion 38 References 40 Appendix 43 Error Calculations 43 The extra resistor from the wires connecting the components in the circuit 43 The effect of temperature on the resistivity of the fixed resistors in the circuit 43 Calculations of best pot 44 Choice of Resistor and Pot 44 Calculation of Frequency Ranges 44 Introduction Shaping and generation of waves is done using electronic circuits known as multivibrators. These circuits produce...
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...An Advanced Finite Element Reliability Tool for Stray Current Corrosion Assessments W.H.A. Peelen and W.M.G. Courage*. TNO Built Environment and Geosciences, P.O. Box 49, 2600 AA Delft, The Netherlands, *wim.courage@tno.nl Abstract: This paper describes a model which simulates stray current interference of underground steel structures through a traction power system, which causes accelerated corrosion Also the coupling of this model to a inhome developed reliability software package, Prob2B, is described. This coupling allows to determine the significance of the input parameters on the accelerated corrosion rate. First preliminary calculations show that uncertainty in the soil resistivity and the train power consumption contribute most in the uncertainty in the maximum interference current density. Keywords: Stray current, corrosion, DC traction power, finite element, reliability calculations. dominant uncertainty is assumed to stem from the train power consumption, which depends on whether it is accelerating or breaking. Of all parameters of the processes occurring in the soil probably the natural corrosion rate, which is accelerated by stray current interference, and the acceleration factor are most influential. Therefore these parameters will be assessed specifically, using reliability analysis tools. 2. Stray Current Corrosion Model An electrical circuit analogue, devoid of the spatial distribution of the problem, of traction power induced...
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...------------------------------------------------- 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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...61826, USA; E-Mails: Richard.G.Lampo@usace.army.mil (R.L.); Michael.K.McInerney@usace.army.mil (M.M.); Jeffrey.P.Ryan@usace.army.mil (J.R.) * Author to whom correspondence should be addressed; E-Mail: chend@ipfw.edu; Tel.: +1-260-481-6356; Fax: +1-260-481-6281. Received: 18 December 2013; in revised form: 1 August 2014 / Accepted: 4 August 2014 / Published: 8 August 2014 Abstract: An innovative prototype sensor containing A36 carbon steel as a capacitor was explored to monitor early-stage corrosion. The sensor detected the changes of the surface- rather than the bulk- property and morphology of A36 during corrosion. Thus it was more sensitive than the conventional electrical resistance corrosion sensors. After being soaked in an aerated 0.2 M NaCl solution, the sensor’s normalized electrical resistance (R/R0) decreased continuously from 1.0 to 0.74 with the extent of corrosion. Meanwhile, the sensor’s normalized capacitance (C/C0) increased continuously from 1.0 to 1.46. X-ray diffraction result indicates that the iron rust on A36 had crystals of lepidocrocite and magnetite. Keywords: carbon steel; chloride; X-ray diffraction; rust; corrosion monitoring Materials 2014, 7 1. Introduction...
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...ABSTRACT The resistivity is a very important property to consider in a drilling fluid. The measurement of resistivity gives us adequate information to know on the concentration of soluble salts. Resistivity is measured by placing the sample in a resistive container having two electrodes spaced so that electrical current can flow through the sample. The main aim of this experiment is to determine the resistivity of the mud sample, the effect of the additives on the mud and then take the measurement using the Analog Resistivity meter. The results were observed and recorded. LIST OF TABLES Table 1.1: showing the result data for the different mud compositions; their corresponding temperatures and resistivity. Table 1.2: showing the result data from the nomograph of the different mud compositions and their concentration of chloride in ppm & percentages. LIST OF FIGURES Figure 1.1: Analog Resistivity Meter Figure 1.2: Beaker Figure 1.3: Spatula Figure 1.4: Mixer...
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...is using the data to produce a 2D cross-section showing the subsurface. This can give a good estimation of both the ore body and the surrounding lithologies, useful information for any future attempt to exploit the resource. Finally, the EM data can be interpreted to carry out depth sounding in one specific area (Reynolds, 2011). Depth sounding, in this context, is working out how deep down the orebody is. Resistivity Background Resistivity is defined as the electrical resistance of an object per unit area measured (Neuendorf et al., 2011). Objects with a low resistivity are good conductors; conversely a high resistivity means that very little current is passing through the material. Resistivity is the inverse property of conductivity; it therefore stands to reason that materials with a low resistivity have a high conductivity. In geological terms, most materials will have a very high resistivity, so a resistivity survey typically depends on fluids trapped in soil and lithological pore spaces to carry the current through the subsurface. The equipment needed for a resistivity survey is relatively simple. Four electrodes are inserted into the ground at known intervals, and are connected to a central control unit, with an attached battery pack. To carry out the survey, the two electrodes at either end discharge a known current into the ground and the two electrodes in the centre create a receiver circuit in which a voltmeter determines how much of the original current is remaining...
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...Correct answers are indicated by LARGE RED text. 29:012 College Physics Exam 1 February 9, 2001 1. Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens? a. protons are removed from the rod b. electrons are added to the rod c. the fur is also charged negatively d. the fur is left neutral 2. A ping pong ball covered with a conducting graphite coating has a mass of 5 Ñ 10€„ kg and a charge of 4 æC. What electric field directed upward will exactly balance the weight of the ball? (g = 9.8 m/s‚) a. 8.2 x 10^2 N/C b. 1.2 x 10^4 N/C c. 2.0 x 10^-7 N/C d. 5.1 x 10^6 N/C 3. The average distance of the electron from the proton in the hydrogen atom is 0.51 Ñ 10€Œm. What is the electron field from the proton's charge at the location of the electron? (k = 9 Ñ 10‹ N m‚/C‚, qe = 1.6 Ñ 10€‹ C) a. 5.5 x 10^11 N/C b. 1.0 x 10^6 N/C c. 3.2 x 10^2 N/C d. 8.8 x 10^-8 N/C 4. Four charges are at the corners of a square, with B and C on opposite corners. Charges A and D, on the other two corners, have equal charge, while both B and C have a charge of +1 C. What is the charge on A so that the force on B is zero? a. -1.0 C b. -0.5 C c. -0.35 C d. -0.71 C 5. Two charges, +Q and -Q, are located two meters apart and there is a point along the line that is equidistant from the two charges as indicated. Which vector best represents the direction of the electric field at that point? a. Vector EA b. Vector EB c. Vector...
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