Review Test 1 Summer 2009
Tuesday, 30-Jun-2009 5:26 PM
Part IV Electricity & Magnetism
Chapter 21: The Electric Field I: Discrete Charge Distributions
21-1 Electric Charge
Charge Quantization, fundamental unit of charge
Charge Conservation, law of conservation of charge, coulomb
21-2 Conductors and Insulators
Charging by Induction
21-3 Coulomb's Law
21-4 The Electric Field
electric field, test charge
Electric Dipoles, electric dipole, electric dipole moment
21-5 Electric Field Lines
lines of force
Chapter 22: The Electric Field II: Continous Charge Distributions
volume charge density, surface charge density, linear charge density
22-2 Gauss's Law
Electric Flux, Gauss's Law, permittivity of free space
22-3 Calculating E from Gauss's Law
Plane Symmetry, Spherical Symmetry
Chapter 23: Electric Potential
23-1 Potential Difference
Continuity of V, Units, Potential & Electric Fields
23-5 Equipotential Surfaces
equipotential region, equipotential surface
The Van de Graff Generator
Examples:
Electric Charge & Coulombs Law: Average Electrostatic & Graviational Forces
Electric Force & Electric Potential
Electric Field due to Electric Dipole (Neutral Water Molecule)
Photoelectric Effect
Surface Charge Density & Total Surface Charge of the Earth
Potential Due to a Group of Point Charges (Charges assembled from inital infinite separations)
Gaussian Surface (inside and outside a hollow pipe)
Calculating Electric Flux through a Rectangle
"Potential" Multiple Choice Questions
The word electric is derived from the Greek word “electron” which means _________________ and when rubbed with wool it would attract other objects.
An atom that has lost or gained one or more electrons is called: _________________
Technique in which a plastic rod can give another object a charge of opposite sign without losing any of its own charge is: _________________
The algebraic sum of all the electric charges in any closed system is constant, charge can be transferred from 1 object to another , & that is the only way in which an object can acquire a net charge; is a description of: _________________
Fact that the fundamental electro-static force between point charges exhibits an inverse-square behaviour is attributed to: _________________
An electric field that is uniform in both magnitude and direction, such field lines penetrate a rectangular surface area, whose plane is oriented perpendicular to the field is a distinction of: _________________
A point charge located outside a closed surface of arbitrary shape in which lines entering the surface equal the number of lines leaving the surface, so the net electric flux through a closed surface that surrounds no charge is: _________________
eV is best for describing emission & absorption of visible light from atoms, and eV is a unit of _________________ NOT of potential.
If force F is conservative, the work done by F is always expressed in terms of: _________________
If the only work done on a particle is done by conservative forces, then –(delta) U gives the total work by:
Ka + Ua = Kb + Ub which represents the:
An electric field can exist at any given point, even if there is no _________________ there to respond to it.
Electric charge always occurs in integral multiples of the fundamental unit of charge e is an example of: _________________
A very large conductor that can supply an unlimited amount of charge is called: _________________
Gauss’s law is a fundamental law of physics that is equivalent to: _________________ for static charges.
For highly symmetric charge distributions, _________________ can be used to calculate the electric field.
Electric potential, which is defined as the _________________, is an important derived physical concept that is related to the electric field.
The Van de Graaff generator produces large potentials in which the charge is brought to the inner surface of a larger spherical conductor by a continuous _________________.
A Van de Graaff accelerator is a device that uses the intense electric field produced by a Van de Graaff generator to accelerate ions, such as _________________.
An electron moving from the negative terminal to the positive terminal of a 12-V car battery loses _________________ of potential energy.
Solar Cells separate the positive & negative charges, i.e. each cell develops a + & - terminal.
History states that positive charges flow in the wires of an electric circuit, but in reality negative charges flow in wires from the negative towards the positive terminal.
An equipotential surface is a 3-D surface on which the electrical potential is the same at every point.
No point can be at 2 different potentials, so equipotential surfaces for different potentials can never touch or intersect.
Cannot choose the shape of equipotential surfaces; the shape is determined by the charge distribution.
Electric force immensely stronger by some 39 orders of magnitude
Dipoles: a system of 2 equal & opposite charges separated by a small distance L.
Magnitude of the Electric Field is also called: "electric field strength"
Induction: technique in which a plastic rod can give another object a charge of opposite sign without losing its own charge.
Charged atom is called an ion.
Positive ion has a net positive charge, negative ion is negatively charged.
Exchange of massless photons is responsible for the electrical force, & the excahnge of massless gravitons accounts for the gravitational force.
Semi-conductors: materials that can be made to behave sometimes as insulators & as conductors
Super-conductors: materials which at low temperatures acquire zero resistance (infinite conductivity) to the flow of charge.
Electric Shielding: The difference between electric & gravitational field is: electric fields can be shielded by various materials, gravitational fields cannot be shielded.
Static charge always lies on the outside surface of any conductor.
Concepts / Terms:
charge, "elektron", charge by induction, ionic solutions, conservation of charge, proportionality constant, field forces, source charge, Gauss's Law, electric flux, electric potential, voltmeter, potential.
1. work done by a force,
2. work done by a conservative force,
3. work-energy theorem
Electric Force & Electric Fields Orders of Magnitude
Field Lines for Charge Distributions
Conductors, Insulators, Electric Dipoles, Ionic Solutions, Induction,
Conservation of Charge
Electric Potential, Voltage
Direction of Current vs Flow of Electrons
Dialectric Breakdown, Strength, & Arc Discharge
Applications of Electrostatics
Lightning can be studied with a Van de Graaff generator, essentially consisting of a spherical dome on which charge is continuously deposited by a moving belt. Charge can be added until the electric field at the surface of the dome becomes equal to the dielectric strength of air. Any more charge leaks off in sparks, as shown in the above figure.
Gauss’s Law
Calculation of the electric flux, number of electric field lines leaving and entering a surface.