Chap 14 Notes Light

7/31/2019 Chap 14 Notes Light

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Physics Chapter 14

Light & Reflection


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14.1 Characteristics of Light

Electromagnetic Wave

a transverse waveconsisting of oscillating electric and magneticfields at right angles to each other.


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Electromagnetic Spectrum

A continuous spectrum of electromagnetic waves

Divided into ranges by frequency (or wavelength)


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All electromagnetic waves move atthe same speedthe speed of light

(3.00 x 108m/s).

WAVE SPEED EQUATION


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Two Factors in Detecting Light:1.Brightness of the source

2.Distance from the source

Follows the inverse-square law

Example: 2 x the distance = as much light

3 x the distance = 1/9 as much light


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14.1 Examples for Problem Solving


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14.2 Flat Mirrors

Reflection

the turning back of anelectromagnetic wave at the surface of asubstance

Diffuserough surface; reflectionsin many directions

Specularsmooth surface; reflectionsin one direction (parallel)

A surface is considered smooth if its surface

variations are small compared to the

wavelength of the incoming [wave].


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14.2 Flat Mirrors

Angle of Incidence angle between a raythat strikes a surfaceand the normal to the

surface at the point ofcontact.

Angle of Reflection angle formed by theline normal to asurface and the

direction in which areflected ray moves.

=


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14.2 Flat Mirrors

Flat mirrorssimplest mirrorsVirtual Image an image formed by lightrays that only appear to intersect

Seen behind the surface of a mirror

Cannot be displayed on a physical surface

Location can be predicted with ray diagrams


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14.2 Flat Mirrors

Ray Diagrams

The image formed by a flat mirror appears to have

right-to-left reversal.


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14.3 Curved Mirrors

Concave Spherical Mirror

inwardlycurved mirror; converges incoming light rays

Real Image formed when rays of light

intersect at a single point

Convex Spherical Mirror

outwardlycurved mirror; diverges incoming light rays;image is always virtual


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14.3 Curved Mirrors

Parabolic MirrorsEliminate spherical abberation

Segments of a 3D parabola

Used in flashlights, headlights, telescopes


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14.4 Color and Polarization

Color of an object depends on1. ..the color (or wavelengths) of light shining on

the object.

2. ..the wavelengths that are reflected

Cone Cells3 types allow humans to see color


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14.4 Color and Polarization

Linear Polarization

The alignment ofelectromagnetic waves in such a way thatthe vibrations of the electric fields in eachof the waves are parallel to each other.

Light can be linear polarized throughtransmission:

Some substances polarize light as it passesthrough

Transmission axis direction of vibrations thatcan pass through a substance

Chap 14 Notes Light

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