Characteristics of light
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Characteristics of Light. Chapter 14 Section 1. Light. Most people think of light as only being admitted from a light bulb or the sun in the form of white light. White light is the combination of multiple colors of light combined into one. Visible Light Spectrum. R ed O range Y ellow

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Characteristics of light

Characteristics of Light

Chapter 14 Section 1


Light
Light

  • Most people think of light as only being admitted from a light bulb or the sun in the form of white light.

  • White light is the combination of multiple colors of light combined into one.


Visible light spectrum
Visible Light Spectrum

  • Red

  • Orange

  • Yellow

  • Green

  • Blue

  • Indigo

  • Violet


Prism
Prism

  • A Prism can be used to separate white light into the colors of the visible light spectrum.


Particle or wave
Particle or wave?

  • Light can be described as a particle, as a wave, and even as a combination of the two.

  • Wave model is best suited for introductory discussion of light.


Light spectrum
Light Spectrum

  • The spectrum of light is not confined to just visible light.

  • There are many variations of light:

    • Radio waves

    • Microwaves

    • Infrared (IR) Waves

    • Visible Light

    • Ultraviolet (UV) Light

    • X Rays

    • Gamma Rays


Electromagnetic spectrum
Electromagnetic Spectrum

  • All of the different kinds of light are examples of electromagnetic waves.

  • Electromagnetic Waves – A transverse wave consisting of oscillating electric and magnetic fields at right angles to each other.


Transverse waves vs longitudinal waves
Transverse Waves vs. Longitudinal Waves

  • Transverse waves oscillate perpendicular to the direction of the wave propagation.

    • Light Waves

  • Longitudinal waves oscillate parallel to the direction of the wave propagation.

    • Sound Waves

      Link:

  • Transverse and Longitudinal Wave Animation


Electromagnetic waves
Electromagnetic Waves

  • Light is composed of electric and magnetic waves.

  • They are perpendicular to the direction they move.

  • They are transverse waves.

  • The electric and magnetic fields are at right angles to each other


Wave differences
Wave Differences

  • Electromagnetic waves are distinguished by their difference in frequencies and wavelengths.

  • They account for the color changes in visible light and distinguishes visible light from invisible electromagnetic radiation, such as X Rays.



Speed of light
Speed of Light

  • All forms of electromagnetic radiation travel at a single high speed in a vacuum.

  • The speed of light in a vacuum was found to be 2.99792458x108 m/s

  • c = 3.00x108 m/s (speed of light)


Wave speed equation
Wave Speed Equation

c = fλ

Speed of Light = frequency x wavelength

  • Speed of Light (c) – Units are in (m/s)

  • Frequency (f) – Units are in (Hz)

  • Wavelength (λ) – Units are in (m)


Example problem
Example Problem

  • What is the wavelength of infrared light with a frequency of 3.0x1012 Hz?


Example problem answer
Example Problem Answer

  • λ = 1.0x10-4 m


Huygens principle
Huygens' Principle

  • The wave nature of light can be treated as a ray.

  • Treating the propagating wave of light as a straight line perpendicular to the wave front.


Brightness of light
Brightness of Light

  • The brightness of light depends on:

    • How much light is being emitted from the source.

    • Distance away from the source.


Brightness and distance
Brightness and Distance

  • Apparent brightness is proportional to the actual brightness of the source divided by the square of the distance between source and observer.

    Lv = L/d2

    Apparent Brightness = Actual Brightness ÷ distance2

  • Brightness – Units (cd) “candela”


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