Physics: EM Waves, Reflection and Refraction, Wave Effect, Mirrors and Lenses, Photoelectric Effect, and Heisenberg Uncertainty Principle Flashcards
What wave forms do/do not need a medium to travel?
Light waves do no need a medium to propagate, unlike other wave forms
What is a red shift vs blue shift?
Redshift and blueshift describe how light shifts toward shorter or longer wavelengths as objects in space (such as stars or galaxies) move closer or farther away from us.
Red moves slower -> red shift, didn’t hear rest
Blue shift as gets closer appear bluer bc faster moving
Transverse wave composed of oscillating ____ and____ magnetic fields
Electric and magnetic
Red shift vs Blue shift
What is Index of refraction (equation and description)?
Blue is toward you, red is away (basically doppler effect for light)
How much slower light travels through medium than through vacuum, see equation sheet for equation
ON EXAM (These relationships) *Law of refraction -> using 2 key equations explain relationship between vmedium, n, and theta
Larger/smaller theta means light bends away from normal and vice versa towards normal
For ___
As v gets faster theta gets bigger
Larger theta means light bends away from normal
They like to ask conceptual questions instead of calc of those 2 formulas
For 0
*Where does light start when you are seeing an object?
Light starts from object being viewed
If you look into water and see a minnow, you start drawing the incident angle from the minnow!
What must be true for there to be total internal reflection/what is total internal reflection?
Total internal reflection -> in order for TIR to occur n1>n2 so theta1
What is polarization of a wave?
The direction in which the wave’s electric field oscillates
The index of refraction of water is about 4/3. Suppose you aimed a laser and a sonar gun (sound waves) from the edge of a lake down toward the water, each with an angle of incidence of 45º. For both light and sound, would the waves bend toward the normal, away form the normal, or not enter the water?
The light rat would partially transmit into the water and would bend toward the normal; the sound beam might partially transmit, but if so would bend away from the normal
Laser is in air, and light starts in air and goes to water, so travels low to high n, thus TIR not possible
Larger n means small angle, and small theta means light bends to normal
Sound speeds up from air to water so it would partially transmit and bend away from the normal
Diffraction is experienced by…
Dispersion is experienced by….
Polarization is experienced by….
What is diffraction?
Diffraction -> light and sound
Dispersion -> only light (prism, common sense ;))
Polarization is experienced by light only
If “door” gets smaller, ppl spread out more when leave door, if door wide, ppl just travled straighter
Diffraction: spreading out of waves when they encounter an obstacle or aperture about the same size as their wavelength; Instead of continuing along the linear path (like a ray of light), they spread out as though emerging from a new point source. For light, this is observable by the pattern of light and dark “fringes” on a screen
These wave effects will be tested qualitatively if at all, DO NOT MEMORIZE EQUATIONS
Why does dispersion occur with light (prism)?
Dispersion occurs bc the the first big rule for waves, that wave speed depends only on the medium and not on the frequency, is not quite true for light
The first big rule states that the speed of a wave is determined by the medium, not by the wave’s frequency, light waves traveling through a material medium are the only exception -> when light travels through different medium, different frequencies will travel at different speeds so when we say the index of refraction (n = c/vmedium) is 1.5, what we really mean is that the index varies slightly as the color of the light varies and bc different colors have diff refractive indexes, they will have different angles of refraction -> this is why when light passes through a prism we see the beam broken into component colors, each color leaves at its own angle of refraction
WE CALL THIS VARIATION IN WAVE SPEED FOR DIFFERENT FREQUENCIES DISPERSION
What does polarization occur? What type of wave can polarize?
What is plane polarization vs circular polarization?
Only transverse waves like light (not longitudinal sound waves)
Normally, light waves have electric fields that oscillate equally in all directions perpendicular to the direction of propagation (remember drawing that looks like star with arrows shooting out circularly)
Polarization occurs when one direction of oscillation is privileged over another, whether by reflection of transmission through a special material or filter
- > Plane polarization: removal of all electric field oscillations except from those along one plane parallel to the direction of propagation
- > Circular polarization: two perpendicular electric field components oscillate 90º out of phase with each other -> superposition of these components creates a filed that rotates in a plane perpendicular to the direction of propagation (looks like spiraling around an axis like a horizontal spiral staircase)
What properties do light waves and sounds waves share?
What properties differ b/w light and sound waves?
reflect, refract, diffract, obey two big rules
Light only: dispersion, polarization, no medium for travel, faster in air than water (opposite for sound)
What do signs of f, i, o, and m mean?
Equation for P (power), focal length, mirror-lense equation, magnification equation
Peep review sheet and equation sheet
Equation for Ephoton, index of refraction (what wave type can it be used for?), Snell’s Law, total internal refraction (what must be true for this scenario?)
Peep equation sheet
