Ch+15+-+Charge+and+Electric+Field

//The main points of this chapter...//
 * Chapter 15: Charge and Electric Field**
 * //Electrical Properties.//
 * //Insulators and Conductors//
 * //Electric Field//
 * //Electric Flux//
 * //Coulomb's Law//

__Electric charge is always conserved__

__Conductors__- materials in that do not allow charge to move freely __Insulators__- materials in which electric charges do not move freely in/on __Semiconductors__- materials that possess electrical properties of both insulators and conductors Electric Force Properties: //this can be summed up by using the following equation to determine electric force//
 * Insulators and Conductors****:**
 * Coulomb's Law:**
 * Inversely proportional to square of separation distance
 * Proportional to product of charge magnitudes
 * Attractive if same charge
 * Repulsive if opposite charge

//where F is force, ke is Coulomb's constant, q1 is charge 1, q2 is charge 2, and r is the distance between the charges. (units Newtons: N)//

Coulomb's constant: 8.99*10^9 Nm^2/C^2 (denoted as ke) Coulomb (SI for unit of charge)

__Electric Field__//-// a force that exists around a charged object that affects other charged objects around it (denoted as E)
 * Electric Field:**
 * Electric field is zero inside conducting material
 * Excess charge on conductor must be entirely on its surface
 * Electric field is perpendicular to surface when just outside conductor
 * Charge moves to smallest radius on irregular objects such as points

E = F/q0 //where E is the electric field, F is force acting (which can be found by the equation above), and q0 is the charge of the test charge// (units N/C)

Electric Force and Field are also seen as: E = ke* [__IqI__/(r^2)] or: F qE

Electric field lines are also used to show the vector and direction of the electric field. See page 478-479 for figure diagrams displaying these lines
 * Electric field lines must start on positive charges and end on negative charges
 * The number of lines displayed is proportional to the magnitude of the charge
 * Field lines never cross

media type="file" key="Movie 78.mov" The above video demonstrates an induced charge. Watch as the straw is charged by the fur. Then as the straw is placed near the neutral paper the papers charge changes so that the two, the straw and the paper, become attracted.

__Electric Flux__- the number of electric field lines that pass perpendicular through a given area (denoted as Φ subscript E)
 * Electric Flux & Gauss's Law:**

//where Φ is electric flux, E is electric field, A is the Area, and theta is the angle of deviation off the perpendicular//

__Gauss's Law__- the electric flux through any closed surface is equivalent to the net charge Q inside the surface divided by the permittivity of free space. Permittivity of free space:

The Millikan Oildrop Experiment (15.7 pg. 483) The Van de Graaff Generator (15.8 pg. 485)
 * Other helpful things to read up on in this chapter include:**