Sun dogs or mock suns are technically called

Sun dogs, or mock suns, are technically called solar parhelia (parhelia meaning "with the sun") and appear as bright bursts of light formed when sunlight passes through ice crystals at the proper angle. Sundogs are formed by plate shaped hexagonal ice crystals in high and cold cirrus clouds refraction

Gabriel’s method of fishing involves spearing the fish while standing on the shore. The actual location of a fish is shown in the diagram below. Indicate on the diagram where Gabriel must aim in order to strike the fish.

• This optical effect is due to refraction. • As light passes from one transparent medium to another, it changes speed, and bends. • How much this happens depends on the refractive index of the mediums and the angle of incidence.

• Angle between the light ray and the normal is called the angle of incidence. • Angle between the light ray and the normal as it enters a new medium is called the angle of refraction.

Each medium has a different refractive index

Draw the refracted ray in each case.

Index of Refraction n Measures the slowing of the speed of light. n= c v c is the speed of light in a vacuum, 3. 0 x 108 m/s v is the speed of light in the other medium.

INDEX OF REFRACTION

Sample problems 1. Calculate the speed of light in ice. 2. The speed of light in a solid is 2. 05 x 108 m/s. What is the solid?

3. What is the speed of light in a) liquid ethyl alcohol (n = 1. 36) and b) solid sodium chloride (n = 1. 54) ? c n = v 8 a) v= 3. 0 x 10 1. 36 vethanol= 2. 2 x 108 m/s

b) c= v. Na. Cl x n 3. 0 x 108= v. Na. Cl x 1. 54 v sodium chloride = 1. 9 x 108 m/s