17 2 waves of the electromagnetic spectrum
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17.2 Waves of the electromagnetic Spectrum . Pg. 578 - 585. What is the Electromagnetic Spectrum? . All electromagnetic waves travel at the same speed in a vacuum, BUT they have different wavelengths at different frequencies

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17.2 Waves of the electromagnetic Spectrum

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17 2 waves of the electromagnetic spectrum

17.2 Waves of the electromagnetic Spectrum

Pg. 578 - 585


What is the electromagnetic spectrum

What is the Electromagnetic Spectrum?

  • All electromagnetic waves travel at the same speed in a vacuum, BUT they have different wavelengths at different frequencies

  • Visible Light: Is radiation in the wavelengths that your eyes can see

    • Only a small portion of electromagnetic radiation is visible light

    • The rest of the wavelengths are invisible


Visible light

Visible Light


What is the electromagnetic spectrum1

What is the Electromagnetic Spectrum?

  • Recall how speed, wavelength, and frequency are related

    • Speed = Wavelength X Frequency

  • As the wavelength decreases, the frequency increases

    • Waves with the longest wavelength have the lowest frequencies

    • Waves with the shortest wavelength have the highest frequencies

    • **The higher the frequency, the higher its energy


What is the electromagnetic spectrum2

What is the Electromagnetic Spectrum?

  • The Electromagnetic Spectrum is the complete range electromagnetic waves placed in order of increasing frequency

  • The Order:

  • Radio Waves, Infrared Rays, Visible Light, Ultraviolet Light, X-rays, and Gamma Rays


Radio waves

Radio Waves

  • Radio Waves are the electromagnetic waves with the longest wavelengths and lowest frequencies

  • There are two types of Radio Waves:

    • 1. Broadcast Waves (Radio and TV)

    • 2. Microwaves


Broadcast waves

Broadcast Waves

  • Radio waves with longer wavelengths are used in broadcasting

  • They carry signals for both radio and television programs


How broadcast waves work

How Broadcast Waves Work

  • A broadcast station sends out radio waves at certain frequencies

  • A radio or TV antenna picks up the waves and converts the radio signals into electrical signals

    • Inside radios the electrical signals are converted into sound

    • Inside TVs the signal is converted into sounds and pictures


Microwaves

Microwaves

  • Microwaves are radio waves with the shortest wavelengths and highest frequencies.

  • Microwaves have many uses

    • Cellular phones, cooking, and radar


Radar

Radar

  • Radar stands for Radio Detection And Ranging

  • Radar is a system that uses reflected radio waves to detect objects and measure their distance and speed


Radar1

Radar

  • To measure distance:

    • A radar device sends out radio waves that reflect off an object

    • The time it takes for the reflected waves to return is used to calculate the object’s distance

  • To measure speed:

    • A radar device uses the Doppler effect

    • The difference in frequency is used to calculate the car’s speed


Infrared rays

Infrared Rays

  • Infrared Rays are electromagnetic waves with wavelengths shorter than those of radio waves


Heat lamps

Heat Lamps

  • Infrared rays have more energy than radio waves

  • You feel the energy of infrared rays as heat

  • Heat lamps have bulbs that give off mostly infrared rays and very little visible light

    • Heat lamps are used to keep food warm or heat up rooms quickly


Infrared cameras

Infrared Cameras

  • Most objects give off some infrared rays

    • Warmer objects give off infrared rays with more energy and higher frequencies

  • Infrared cameras take pictures using infrared rays instead of light

    • These pictures are called thermograms, which is an image that shows regions of different temperatures in different colors

    • Used by firefighters to locate people during fires


Visible light1

Visible Light

  • Visible light are electromagnetic waves that we can see

  • Visible light has shorter wavelengths and higher frequencies than infrared rays

    • Visible light with the longest wavelength appear red

    • Visible light with the shortest wavelength appear violet in color


Ultraviolet rays

Ultraviolet Rays

  • Ultraviolet Rays are electromagnetic waves with wavelengths shorter than those of visible light

  • Ultraviolet Rays have higher frequencies than visible light so they have more energy

    • Have enough energy to damage or kill living cells

    • Ultraviolet lamps are used to kill bacteria on hospital equipment


Ultraviolet rays and health

Ultraviolet Rays and Health

  • Small doses of ultraviolet rays are useful!

    • Cause skin to produce vitamin D, which is needed for healthy bones and teeth

  • Large doses of ultraviolet rays can be harmful!

    • Can burn your skin, which causes skin cancer and damage to your eyes

    • By applying sun block and wearing sunglasses you can limit the damage caused by ultraviolet rays


X rays

X-Rays

  • X-Rays are electromagnetic waves with wavelengths just shorter than those of ultraviolet rays

  • X-Rays have higher frequencies than ultraviolet rays = more energy

  • X-Rays have so much energy they can penetrate most matter except bone

    • Bones absorb X-rays


How x rays work

How X-Rays Work

  • Bones absorb X-rays and does not allow them to pass through

  • X-rays pass through skin and soft tissue, causing the photographic film in the X-ray machine to darken when it is developed

  • Bones absorb the X-rays and appear as the lighter areas on the film


X rays1

X-Rays

  • Too much X-ray exposure can cause cancer

    • When X-rays are taken a lead apron is worn during the procedure

    • The lead apron absorbs the X-rays and prevents them from reaching your body


Uses of x rays

Uses of X-Rays

  • X-rays are sometimes used in industry and engineering

    • Used to find out if steel has any tiny cracks because the X-rays will pass through the tiny cracks that are not visible to the human eye

    • Used to check the quality of joints in oil and gas pipelines


Gamma rays

Gamma Rays

  • Gamma Rays are electromagnetic waves with the shortest wavelengths and highest frequencies

  • Gamma Rays have the most energy

    • Are the most penetrating of all of the electromagnetic waves


Uses of gamma rays

Uses of Gamma Rays

  • Radioactive substances and nuclear reactions produce gamma rays

  • Gamma rays are also used in medicine

    • Used to kill cancer cells inside the body

    • Used to examine internal body structures

      • A patient will be injected with fluid that emits gamma rays

      • The gamma ray detector can form an image of the inside of the body


Gamma rays and space

Gamma Rays and Space

  • Some objects in space give off bursts of gamma rays

  • Gamma Rays are blocked by Earth’s atmosphere

    • Gamma ray telescopes that detect the gamma rays must orbit above the Earth’s atmosphere

  • Astronomers believe that explosions of stars in the distant galaxies are one way of producing gamma rays


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