Course Introduction and Electric Chargepages.erau.edu/~snivelyj/ps250/PS250-Lecture1.pdf · Course...
Transcript of Course Introduction and Electric Chargepages.erau.edu/~snivelyj/ps250/PS250-Lecture1.pdf · Course...
PS 250: Lecture 1 Course Introduction and Electric Charge
J. B. Snively August 24, 2015
Today’s Class
Friendly Introductions! Syllabus and Course Format Introduction to Electric Charge Summary
Part 1: Electrostatics
Chapter 21: Electric charge and the electric field
Chapter 22: Gauss’s Law
Chapter 23: Electric Potential
First exam covers basics of electrostatics!
Part 2: Capacitors, Circuits, Current...
Chapter 24: Capacitance and Dielectrics
Chapter 25: Current, Resistance, Electromotive Force
Chapter 26: Direct-current (DC) Circuits
Chapter 27: Magnetic Fields and Forces
Second exam covers basics of electric current, circuits, and magnetic forces!
Part 3: Magnetic fields, induction, inductance...Chapter 28: Sources of Magnetic Fields
Chapter 29: Electromagnetic Induction
Chapter 30: Inductance
Third exam covers basics of magnetic fields and electro-magnetics, including the coupling between electric and magnetic fields.
Part 4: Electromagnetic Waves, Modern Physics...
Chapter 32: Electromagnetic Waves
Chapter 37: Special Relativity
Chapter 38: Basics of Atomic Physics
Comprehensive final exam covers ALL topics previously discussed, plus basics of electromagnetic waves (light / radio) and modern physics!
Today’s Class
Friendly Introductions! Syllabus and Course Format Introduction to Electric Charge Summary
What is Charge?Characterized as Negative or positive
Fundamental property of matter which is:
Conserved (due to transfer of persistent individual charge carriers, typically electrons)
Quantized (due to discrete nature of electrons and other charged particles)
“Electrostatics”: Behavior of charges that are at rest (i.e, static).
Conservation and Quantization of ChargeCharge cannot be created or destroyed. Therefore: Charge is (Universally) Conserved: “The algebraic sum of all the electric charges in any closed system is constant.”
Charge is defined by individual subatomic particles (electrons/protons). Therefore: Charge is Quantized: “The magnitude of charge of the electron or proton is a natural unit of charge.”
Structure of an Atom
Neutral atoms may gain/lose electrons, resulting in “Ions”
Positive Ion: Fewer electrons than protons
Negative Ion: More electrons than protons
“Ionization” is the process of gaining / losing electrons.
Charging by Friction
-+
“Opposite” Charges Attract:
--
“Like” Charges Repel:
++
Glass tends to lose electrons, plastic tends to hold on to electrons
Total charge remains constant – Shared between ball, rod,
and the conductive wire.
Charging by Conduction
Charging by Induction
The negatively charged rod induces an accumulation of negative charge on opposite
side of the metal ball.
Polarization
Even uncharged insulators are weakly affected by the presence of external charges.
Material PropertiesInsulators (Dielectrics): Typically non-metals, which do not allow free motion of charge – Charge accumulates on and within.
Conductors: Typically metals, which allow free transfer of charge. Electrons move freely, and charge accumulates on surface.
Semiconductors: Intermediate materials which allow charge to move under certain conditions – Basis for “nonlinear” circuit elements (diodes, transistors).
Summary / Next Class:
Read Textbook Sections: 21.1–21.4
Figure out how to access Mastering Physics Course “PS250SNIVELYFA15”
Visit website! The online syllabus/schedule is always the preferred version.
Prepare to discuss!