CP Physics Chapter 15

Refraction and Lenses

Refraction of Light

• Change of velocity• Change of wavelength

v

cn

Example #3

How fast does light travel through diamond?

Change in direction

21 nn

2121 nnnn

Fig 35-13, p.1104

Example #4What is the angle of refraction of a light ray entering water from air at an angle of 30 degrees?

Example #5

At what angle does the light ray exit into the flint glass?

water

ethanol

flint glass

38°

Example #6How far are you (1.8 m tall) standing from the edge of a pool, if you see a fish under water? The fish is actually 0.9 m deep and 0.5 m from the edge of the pool. Assume that the pool is completely filled. B. What is the apparent depth of the fish?

Example #7

What is the refracted angle of a light ray going from diamond at 37-deg into air?

Critical Angle and T.I.R.

Fiber Optics

Example #8What is the critical angle of a ray going from diamond into air?

Mirages

Rainbows

Formation of Rainbows

Why is the sky blue during midday and reddish/orange at sunset or sunrise?

Convex Lens (Converging Lens)

F F

Focal Point of a Convex Lens

Fig 36-34, p.1152

Spherical Aberration

Fig 36-35, p.1153

Chromatic Aberration

Example #6What is the focal length of a convex lens if an image is located 4.5 cm in back of the lens and the object is placed at the same location but in front of the lens? what is the magnification of the lens?

Example #7A magnifying glass is used to magnify the image of an insect that is placed 3 cm in front of the lens with a radius of curvature of 10 cm. Where is the image located?

Concave Lens (Diverging Lens)

Example #8Where is the image located if an object is placed 5 cm in front of a 6 cm concave lens? What is the magnification of the lens? If the image is 1.1 cm tall, what is the size of the object?

Example #9The magnification of a particular lens is to magnify an object by +3.5 times its original size. If the object is placed 4 cm in front of the lens, where is the image located and the focal length of the lens?

Example #10A lens is used to magnify an image by 0.4 times. If the image is RSU and the focal length is 5 cm,

A) where must the image and object be placed?

B) How far apart are the image and object?

Vision• 20/80 vision• Diopter/lens power• eyeball

Nearsighted

Farsighted

Astigmatism