Flashcards in Chapter 19 Deck (17):
what is a mirage?
a mirage can be observed when the air just above the ground is warmer than the air above it. Hot air is less dense than cool air, so it has a lower index of refraction, therefore light is refracted
how does atmospheric refraction relate to the sunset?
light rays from the sun are bent as they pass through the atmosphere. Light passes through layers of the atmosphere, each with a slightly different index of refraction. The sun is seen to be above the horizon after it has fallen below it
What is a camera?
A camera is a light-tight chamber, with a converging lens that produces real image on a film (or CCD detector)
what does the shutter of a camera do?
The shutter opens for specified exposure times
what does the aperture do in a camera?
the aperture is adjustable
how can you focus a camera?
by adjusting the lens-film distance
what is accommodation?
How the eye focuses; muscles adjust the radius of curvature of the pliable lens to bring objects at different distances into focus
what is farsightedness (hyperopia)?
near point (25cm) when people can see faraway objects well but not nearby objects
fix with converging lens (positive)
what is nearsightedness (myopia)?
far point (infinity) when people can see nearby objects well but faraway objects are blurry
fix with diverging lens (negative)
what are corrective lenses?
2 lenses, one which is your glasses, the other is your eye
the lens produces an intermediate virtual image of the object within the accommodation range so that the final image appears on the retina
lens power is measured in?
diopters; 1D = 1/m
P = 1/f
θobject = h/s
θimage = h'/s'
What is the formula for angular magnification?
M = θimage/θobject = h/f = h'/s'
what does s' mean in this unit?
s' = near point
and far point os always equal to infinity so it equals 0
What are the different parts to finding the angular magnification for a compound microscope?
1. Magnification of the eyepiece: Me = 25cm/fe
2. Magnitude of Objective: Mo = -s'/s = -L/fo