Electromagnetic Spectrum

1
Electromagnetic Spectrum

• Chapter 17 18

2
Electromagnetic Waves

• Electromagnetic waves are transverse waves that
  have some electrical properties and some magnetic
  properties.
• An electromagnetic wave consists of changing
  electric and magnetic fields.

3
Electromagnetic Radiation

• The energy that is transferred by electromagnetic
  waves is called electromagnetic radiation.
• All electromagnetic waves travel at the same
  speed 300,000, 000 m/s.

4
Wave or Particles?

• Light has many of the properties of waves. But
  light can also act as though it is a stream of
  particles.
• When light passes through a polarized filter, it
  has the properties of a wave.

5
Wave or Particles?

• When a beam of light shines on some substances,
  it causes tiny particles called electrons to move
  (photoelectric effect).
• Light is a stream of tiny packets or particles
  known as photons.

6
Characteristics of Electromagnetic Waves

• All electromagnetic waves travel at the same
  speed, but they have different wavelengths and
  different frequencies.
• Remember
• Speedwavelength x frequency

7
Different Wavelengths of the Electromagnetic
Spectrum

• In order of decreasing wavelength
• Radio
• Infrared
• Visible light
• Ultraviolet
• X ray
• Gamma ray

8
What happens to light when is strikes a surface?

• Light can be reflected, absorbed or transmitted
  when it strikes a surface.
• You can not see through objects that are opaque.
• A transparent material transmits light.
• Translucent materials scatter light as it passes
  through.

9
Types of Reflection

• Regular reflection occurs when the light waves
  hit a smooth surface.
• Diffuse reflection occurs when the light waves
  hit a rough surface and the light waves are
  scattered.

10
Types of Mirrors

• Concave mirrors are mirrors that curve inward.
  These type of mirrors can produce virtual real
  images.
• Convex mirrors are mirrors that bulge outward.
  These type of mirrors can produce virtual images.
• Plane mirrors produce virtual images.

11
Type of Images

• Real images are inverted images formed where rays
  of light meet.
• Virtual images are upright images formed where
  rays of light appear to meet or come from.

12
Refraction

• Refraction happens when light waves changes speed
  as it goes through different mediums.
• As light waves change speed the waves bend.

13
Effects of Refraction

• Refraction makes objects appear to be in
  different positions.
• Refractions in the atmosphere creates mirages.

14
Rainbows

• Raindrops act like tiny prisms, refracting and
  reflecting the light and separating the colors.
• ROY G BIV
• Red
• Orange
• Yellow
• Green
• Blue
• Indigo
• Violet

15
Mirage

• A mirage is an image of a distant objects caused
  by refraction of light.

16
Which form of electromagnetic wave has the
shortest wavelength, but the greatest energy?

• Radio waves.
• Visible light waves.
• Ultraviolet wave.
• Gamma rays.

17
An electromagnetic wave is what type of wave?

• Longitudinal wave.
• Surface wave.
• Transverse wave.
• Mechanical wave.

18
Lenses

• A lens is a curved piece of glass.
• Lenses can magnify images.
• Magnification is any change in the size of an
  image compared with the size of the object.

19
Type of Lenses

• Converging lens bends the light inward that
  produces a virtual or real image. (convex lens)
• Diverging lens bends the light outward and can
  produce only a virtual image. (concave lens)

20
Correct Vision

• Nearsightedness is when you only see things
  clearly that are close.
• Eyeball is too long.
• Corrected by concave lens.
• Farsightedness is when you only see things
  clearly that are far.
• Eyeball is too short.
• Corrected by convex lens.

21
Which type of lens converge light to a focal
point?

• Concave.
• Convex.
• Both concave and convex.
• Neither concave nor convex.

22
Which type of lens is used to correct nearsighted
vision?

• Concave.
• Convex.
• Both concave and convex.
• Neither concave nor convex.

23
Other Uses of Light Lenses

• Telescopes
• Microscopes
• Cameras
• Lasers
• CDs
• DVDs
• Optic Fibers
• Communications
• Surgery

24
Colors

• The color we see is the light being reflected
  from the object.
• Additive primary colors are red, green blue.
• Subtractive primary colors are yellow, cyan and
  magenta.

25
Colors and Pigments

• If all colors are reflected, you see white light.
• If all colors are absorbed, you see black.

26
Review Questions

• What type of wave is light?
• Transverse
• What is the longest wavelength of the
  electromagnetic spectrum?
• Radio
• Which type of electromagnetic waves have the most
  energy?
• gamma

27
Review Questions

• What are the three primary colors?
• Red, blue, green
• What is the speed of light?
• 300,000 km/s
• Which type of lens converges light to a focal
  point?
• Convex

28
Review Questions

• Which type of mirror produces either a virtual or
  real image?
• Concave
• Which type of image is up-side-down?
• Real
• What do we call objects that only reflect light?
• opaque

29
Review Questions

• What do we call objects that transmit light?
• Transparent
• What do we call objects that dont transmit light
  clearly?
• Translucent
• Which type of lens corrects nearsightedness?
• concave

30
Review Questions

• Which type of lens corrects farsightedness?
• Convex
• What happens when light is bent as it changes
  medium?
• Refraction
• What happens when light reflects off of an
  surface?
• Reflection

31
Review Questions

• The End
• Study!!!!!!!!!!!!!!!!!!!!