# Shared Flashcard Set

## Details

CH 22 Electromagnetic Waves
concepts and formulas
12
Physics
04/01/2013

Term
 Maxwell's equations are used to explain
Definition
 electric and magnetic fields  aka electromagentic theory
Term
 Write all 4 of Maxwell's equations (in words)
Definition
 1. Gauss Law:ΦE= EAcosθ (relates electric flux to its source; the electric field,charge and the area. 2.  an similar equation for magnetic flux except that magnetic field lines do not end (like electric field lines). 3. Faraday's law: an electric field is produced by a changing magentic field 4. Ampere's law: a magentic field is produced by an electric current OR BY A CHANGING ELECTRIC FIELD (proved by Maxwell)
Term
 A current produced by a changing electric field is called a _____ current.   An ordinary current is called a ____ current.
Definition
 1. displacement current (ID)   2. conduction current
Term
 describe what an electromagnetic field is
Definition
 electromagnetic waves is a wave of interchanging magentic and electric fields that can propagate and travel throughout space.   aka: if a changing magnetic field produces an electric field= that electric field is changing= this will in turn produce a magentic field
Term
 The magintudes of B & E decrease with ____
Definition
 distance (1/r)
Term
 The energy carried by the electromagnetic wave is proportional to ____ and the intesity of the wave decreases with ______
Definition
 1. square of the amplitude (E2 or B2) 2.  1/r2
Term
 Electric and magnetic fields at any point are (perpendicular/parallel )to each other and is ( perpendicular/parallel )to the direction of  wave travel
Definition
 perpendicular for both blanks
Term
 t or f: when electromagnetic waves travel through an empty space, there are no charges for the electric field lines to start or stop on.
Definition
 true
Term
 true or false: magnetic lines always form closed loops.
Definition
 true
Term
 why can Electromagentic waves propragate in an empty space?
Definition
 b/c they are waves of fields (not of matter like water)
Term
 what gives rise to electromagentic waves?
Definition
 acclerating electrical charges
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