Physics C Chapter Chapter 35 From serway book Prepared by Anas A. Alkanoa Prepared by Anas

47 Pages·2013·1.16 MB·English

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Chapter Seven
The Nature of Light and the
Laws of Geometric Optics
35.1 The Nature of Light
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35.5 Refraction
35.6 Huygens’s Principle
35.7 Dispersion and Prisms
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35.1 The Nature of Light
1678
In , the Dutch physicist and astronomer Christian Huygens
showed that a wave theory of light could also explain reflection and
refraction.
In 1801 1773–1829
, Thomas Young ( ) showed that, under
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Maxwell, in 1873 asserted that light was a form of high-frequency
electromagnetic wave.
Although the wave model and the classical theory of electricity and
magnetism were able to explain most known properties of light, they
could not explain some subsequent experiments.
An explanation of the photoelectric effect was proposed by Einstein in
1905
in a theory that used the concept of quantization developed by
1858–1947 1900.
Max Planck ( ) in
The quantization model assumes that the energy of a light wave is present
in particles called photons; hence, the energy is said to be quantized.
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where h = 6.63×10−34 J.s is Planck’s constant
Light exhibits the characteristics of a wave in some situations and
the characteristics of a particle in other situations.
35.3 The Ray Approximation in Geometric Optics
The field of geometric optics involves the study of the propagation of
light, with the assumption that light travels in a fixed direction in a
straight line as it passes through a uniform medium and changes its
direction when it meets the surface of a different medium or if the
optical properties of the medium are nonuniform in either space or
ttiimmee..
Ray approximation:
λ
The ray approximation and the assumption that << dare used in
this chapter and in Chapter 36, both of which deal with geometric optics.
This approximation is very good for the study of mirrors, lenses, prisms,
and associated optical instruments, such as telescopes, cameras, and
eyeglasses.

35.4 Reflection
When a light ray traveling in one medium encounters a boundary with
another medium, part of the incident light is reflected.
Reflection of light from such a smooth surface is called ssssppppeeeeccccuuuullllaaaarrrr
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Reflection from any rough surface is known as ddddiiiiffffffffuuuusssseeee rrrreeeefffflllleeeeccccttttiiiioooonnnn.
θ'
θ
The incident and reflected rays make angles and , respectively,
1
1
where the angles are measured between the normal and the rays.
Experiments and theory show that the angle of reflection equals the
angle of incidence: θ' = θ
1
1
This relationship is called the llllaaaawwww ooooffff rrrreeeefffflllleeeeccccttttiiiioooonnnn.