{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Physics 52 Final Exam Study Guide(7)_2

# Physics 52 Final Exam Study Guide(7)_2 - Physics 52"Study...

This preview shows pages 1–2. Sign up to view the full content.

Physics 52 "Study Guide" for Final Exam ("Laundry List" of important concepts) Todd Sauke Concept (important concepts in bold; vectors also shown in bold ) Symbol or Equation Prerequisites: From mechanics , total external force on a body = mass x acceleration Σ F ext = m a (SI newton, "N") Mass (SI kilogram, "kg") resists change in motion (via " momentum" , p ) p = m v , F ext = d p /dt A moving mass has energy of motion, " Kinetic Energy " (SI joule, "J") KE = ½ m v 2 (a scalar) Electric Charge is conserved, quantized, comes in "positive" and "negative" e = 1.602 x 10 -19 C Like charges repel ( radially ); opposite charges attract; Coulomb's Law F = (1/(4 π ε 0 )) q 1 q 2 / r 2 All "normal" matter is made up of protons, neutrons and electrons m p = 1.67 x 10 -27 kg Protons have +e charge; electrons have –e. Their mutual attraction holds m e = 9.11 x 10 -31 kg everything together. In a conductor, electrons are free to move around. Maxwell's Equations show that Light is an Electromagnetic wave c = 1/ ε 0 μ 0 = 2.998 x 10 8 m/s Electromagnetic waves are transverse w/ E , B to each other and propagation E(x,t ) = E max cos(kx- ω t) "k" is the wave number of a propagating sinusoidal electromagnetic wave k = 2 π / λ E max = c B max There are two possible polarizations of light for x-propagation ( E in y or E in z) (or tilted in y-z plane) For an electromagnetic wave traveling in a dielectric (eg. glass) v < c v 2 = 1 / ( ε μ ) = c 2 / K K m K is called the dielectric constant of a medium. K m is relative permeability . K m ~ 1.00 for most dielectrics Visible light is but a small part of the spectrum of electromagnetic waves λ xray < λ uv < λ vis < λ ir < λ μ wav < λ tv Light and Optics: Light waves typically appear to travel in straight lines called light rays . Because of the way that light forms shadows and appears to travel in rays, people were led to think of light as a stream of particles. But then wave properties (of very short wavelength) were noticed and light became recognized as a wave. λ vis ~ 400 – 700 x 10 -9 m Light has both wave and particle properties. Light propagates as a wave. Maxwell's Equations Æ light is generated (emitted) by accelerating electric charges When light interacts with matter, it is emitted or absorbed in "packets" of Quantum mechanics energy called photons . This packet aspect of light gives it a particle nature. (another course of study) In this course, we (mostly) confine our study of light to its wave nature. Light rays are a graphical tool Light rays are drawn perpendicular to the wavefronts of a light wave. θ a θ r θ b a b We draw light rays to represent light traveling through a region of space. When we draw light rays reflecting off a boundary or being transmitted (refracted) into another medium, we define angles with respect to the surface perpendicular. _______ __ The ratio of the speed of light in vacuum to that in some medium is n = c / v; n = K K m ~ K called the index of refraction , n , of the medium. n is always 1.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}