24 - MasteringPhysics: Assignment Print View

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MasteringPhysics: Assignment Print View http://session.masteringphysics.com/myct/assignmentPrint?assig. .. 1 of 12 17/4/07 15:38 [ Assignment View ] E ð lisfræ ð i 2, vor 2007 24. Capacitance and Dielectrics Assignment is due at 2:00am on Wednesday, February 7, 2007 Credit for problems submitted late will decrease to 0% after the deadline has passed. The wrong answer penalty is 2% per part. Multiple choice questions are penalized as described in the online help. The unopened hint bonus is 2% per part. You are allowed 4 attempts per answer. Introduction to Capacitance Introduction to Capacitance Learning Goal: To understand the meaning of capacitance and ways of calculating capacitance When a positive charge is placed on a conductor that is insulated from ground, an electric field emanates from the conductor to ground, and the conductor will have a nonzero potential relative to ground. If more charge is placed on the conductor, this voltage will increase proportionately. The ratio of charge to voltage is called the capacitance of this conductor: . Capacitance is one of the central concepts in electrostatics, and specially constructed devices called capacitors are essential elements of electronic circuits. In a capacitor, a second conducting surface is placed near the first (they are often called electrodes ), and the relevant voltage is the voltage between these two electrodes. This tutorial is designed to help you understand capacitance by assisting you in calculating the capacitance of a parallel-plate capacitor, which consists of two plates each of area separated by a small distance with air or vacuum in between. In figuring out the capacitance of this configuration of conductors, it is important to keep in mind that the voltage difference is the line integral of the electric field between the plates. Part A What property of objects is best measured by their capacitance? ANSWER: ability to conduct electric current ability to distort an external electrostatic field ability to store charge ability to store electrostatic energy Capacitance is a measure of the ability of a system of two conductors to store electric charge and energy. Capacitance is defined as . This ratio remains constant as long as the system retains its geometry and the amount of dielectric does not change. Capacitors are special devices designed to combine a large capacitance with a small size. However, any pair of conductors separated by a dielectric (or vacuum) has some capacitance. Even an isolated electrode has a small capacitance. That is, if a charge is placed on it, its potential with respect to ground will change, and the ratio is its capacitance . Part B
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This note was uploaded on 11/02/2009 for the course MASTERING PHYS taught by Professor All during the Spring '09 term at Kettering.

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24 - MasteringPhysics: Assignment Print View

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