AP Physics IV.C

Geometric Optics

25.1 Wave Fronts and Rays

25.2 Reflection of Light

Specular and diffuse reflection

25.3 Plane Mirrors

Five Properties of the image of a Plane Mirror

• Upright

• Same size

• Located as far behind the mirror as the object is in front of the mirror

• Left to right reversed

• Virtual image

Ray Diagram for a Plane Mirror

Ex. What is the minimum mirror height needed for a person to see their full image?

25.4 Spherical Mirrors (concave – converging and convex –

diverging)

The focal length and radius of curvature

Ray diagrams for curved mirrors

25.6 The mirror equation and magnification (and an impressive

proof thrown in for free)

Summary of sign conventions for curved mirrors

• f is positive for a concave mirror and negative for a convex mirror

• so is positive for an image located in front of the mirror (our only concern at this point)

• si is positive for a real image (in front of the mirror) and negative for a virtual image (behind the mirror)

Ex. A 2.00 cm object is placed 7.10 cm from a concave mirror whose radius of curvature is 10.20 cm. Find the location and size of the image.

Ex. An object with a height of 1.20 cm is placed 6.00 cm in front of a concave mirror with a focal length of 10.0 cm. Find the location and height of the image.

Ex. An object is placed 66 cm in front of a convex mirror that has a focal length of 46 cm. Find the image distance and magnification.

26.1 Refraction and Lenses

Refraction – the bending of light as it passes between two media with

different optical densities

The index of refraction

p. 821: 1-6; Rev. 04B3, 04B5

2. 0.54114. 1.63, ?6. 0.80004B3a) 1.2 EE -3 Wbb) -0.0136 Vc) i. 0.023 A ii. ?d) ?

04B5a) i. -3600 J

ii. Tough one – ΔU is number of gas particles times ΔKav (5400 J)

iii. 9000 Jb) Drawingc) i. drawing ii. yours

26.2 Snell’s Law

Ex. Light is incident upon an equilateral crown glass prism at an angle of 45.0º to one face. Calculate the angle at which the light emerges from the opposite face.

p. 821: 9-10, 13, 16; Rev. 03B1

10. 21.7º16. a) 33º b) 32º03B1a) Drawingb) 100 Nc) 615 Nd) Yourse) 1.7 m/s2

26.3 Total Internal Reflection

Ex. A ray of light in a diamond (n = 2.42) strikes an interface at 28º. Will the beam of light enter the air or will it be reflected internally? Will the beam of light be reflected internally if the diamond is surrounded by water?

Applications of total internal reflection

26.5 Dispersion of Light

p. 822: 23-25, 87B5, 01B4

24. 37.8º87B5a) ?b) 53ºc) 1.9 EE 8 m/sd) 3.2 EE -7 m (320

nm)e) 39º

01B4a) 1.6 (hint: use slope of

graph and Snell’s Law)

b) i. 4.4 EE 14 Hzii. 1.9 EE 8 m/siii. 4.3 EE -7 m

c) Drawingd) 37º

26.6 Lenses

Two types of lenses

Images formed by converging lenses

Image formed by a diverging lens

A familiar friend

Sign conventions for lenses:

f is positive for converging lenses and negative for diverging lensesso is positive when light is reflected from the object (a real object)si is positive when it is behind the lens (real image) and negative when it is in front of the lens (virtual image)

81B5, 82B6, 86B6, 94B5

81B5a) Drawing b) ?c) 9 cm d)

note: 2nd lens is at F of 1st

82B6 a) 3f b) drawing

c) ?86B6 a) drawing b) 6 cm

c) Drawingd) -2 cm e) ?f) Hint: use image of 1st

lens as object of 2nd

94B5 a) 2.3 EE 8 m/sb) Drawing c) 49ºd) 40 cm below pool

bottome) i. ? ii. Hint: are

values for n closer or farther away than in water?