Chapter 23; Mirrors and Lenses

When a wave reaches a boundary between two mediums and is turned around

reflection boundary with a more rigid medium

reflection boundary with a less rigid medium

Flat mirrors which form a virtual image

• - Images same size and orientation
• - Image left to right
• - Must be half the height of the object to see entire object

Line perpendicular to the mirror; passes through the center of curvature

The geometric center fo the sphere

1/2 of the Center of Curvature

Distance from the mirror to the object

• - real image (formed in front of the mirror)
• - image inverted (always)
• - image smaller than object
• - focal length positive

• - virtual image (image formed behind mirror)
• - image upright
• - image larger than object
• - focal length positive

• - virtual image (formed behind mirror)
• - image upright
• - image smaller than object
• - exchanges field of view for size (larger field; smaller size)
• - reflective on the outside
• - focal length negative

be reflected through the focal point

reflected parallel to the principle axis

the image is virtual

the image is real

POSITIVE!

• 1/f = 1/d_i + 1/d_o
• m = h_i/h_o = -d_i/d_o

the image is upright

the image is inverted

P = 1/f

measured in diopters(1/m); focal lenght MUST be in meters

• n_osinO_i = nsinO_r (n_o - moving out of; n - moving in to)
• n=(sin i)/(sin r)

n=C/v_s

• If you are going out of a substance into air, you use the reciprocal of the n value
• (C = 3x10⁸ m/s)

If you are going from one substance into another, you find the n for the boundary by dividing the n value of what you are going into by the n value of what you are leaving

the bending of light at a boundary; if the speed in the new medium is less than the speed of the old, the wave bends toward the normal line, and vise versa

Convex (curve out); make light converge earlier; focal length positive

Concave (curve in); diverge light; focal length negative

• - Real images appear on the same side as object
• - Virtual images appear behind the mirror
• - Object distances always positive
• - Image distance is negative

• - Real images appear on the opposite side of the object
• - Virtual images appear on the same side of the lens
• - Object distances are always positive
• - Image height positive = upright
• - Image height negative = inverted
• - Can only cast real images onto a screen
• - d_i = negative if on same side as object; vise versa

• - lens focuses image on the retina
• - image formed in front of retina = nearsighted
• - image formed behind the retina = farsighted

- nearsight: too much convergence; use diverging lenses to correct; can only do lasic on nearsighted people

- farsight: too much divergance; use converging lens to correct