PHY 132 T3 Formulas

Law of Reflection

angle of incidence = angle of reflection

Focal Length of Spherical Mirror

ignoring spherical abberation. f = focal length; r = radius of curvature of spherical mirror

Mirror/ Lens Equations

Where

• d0 = object distance from mirror/lens

• di = image distance from mirror/lens

• f = focal length

• m = magnification

• hi = image height

• ho = object height

index of refraction

where

• n = index of refraction

• v = speed of light in that material

• c = speed of light in a vacuum (3 × 10^8 m/s)

Law of Refraction/Snell’s Law

where

n1 = index of refraction of medium 1

theta 1 = angle of light in medium 1

n2 = index of refraction of medium 2

theta 2 = angle of light in medium 2

Total Internal Reflection

where

n1 = index of refraction of medium 1

theta c = critical angle

n2 = index of refraction of medium 2

Magnification of Magnifying Glass

Where

M = magnification

theta’ = angle image makes with eye

theta = angle object makes with eye

Magnification of eye focused for near point (no object distance)

where

M = magnification

N = near point (usually 25cm)

f = focal length

Magnification of “relaxed” eye

where

M = magnification

N = near point (usually 25 cm)

f = focal length

Image size

where

s = image size

theta = angle that object “occupies” in the field of view

f = focal length

Angular Resolution

theta res = angular resolution

lambda = incoming light wavelength

D = device diameter

Snell’s Law (Waves)

where

n1 = index of refraction of medium 1

lambda 1 = light wavelength in medium 1

n2 = index of refraction of medium 2

lambda 2 = light wavelength in medium 2

speed of light (waves)

where

c = speed of light

lambda = wavelength

f = frequency

Constructive Interference

where

d = gap between slits

lambda = light wavelength

m = whole number order

Destructive Interference

where

d = gap between slits

lambda = light wavelength

m = whole number order