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Electromagnetic Spectrum PowerPoint Presentation
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Electromagnetic Spectrum

Electromagnetic Spectrum

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Electromagnetic Spectrum

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  1. Electromagnetic Spectrum

  2. Open your textbooks to Page 380 “Light and Colour”

  3. Let’s read page 382 and 383 “Energy in a Wave”

  4. Write the definitions for the bolded terms on page 382 and 383 into your notebook You have 8 minutes...GO

  5. Electromagnetic Spectrum • Visible light is only a tiny fraction of the energy that surrounds us every day • We are surrounded by invisible light-like waves, which together with visible light are called “electromagnetic radiation” • Electromagnetic radiation is a wave pattern made of electric and magnetic fields that can travel through empty space • The entire range of electromagnetic radiation is called the Electromagnetic Spectrum

  6. Electromagnetic Spectrum Writing Activity • With a partner, write a SHORT definition for each type of wave and ray found in the electromagnetic spectrum • Draw a diagram of the spectrum in your notes

  7. Colour Wavelengths & The Visible Spectrum • Light travels in waves • Each colour of the rainbow has its own wavelength • Wavelengths are measured in nanometres. • One nanometre is equal to one billionth of a meter. • Our eyes can only detect wavelengths approximately between 390 – 750 nm • Red has the longest wavelength, while violet has the shortest wavelength

  8. Approximate Wavelengths of the Visible Spectrum

  9. Relationship Between Frequency (Hz) and Wavelength of Colours • Frequency is the rate of repetition in a cycle • 1 Hz is equal to 1 wave cycle per second The longer the wavelength, the less the frequency The shorter the wavelength, the higher the frequency

  10. Blue Sky vs. Red Sunset • Air will scatter short-wavelength light in preference to long-wavelength light. • Long-wavelength light will pass through the air • The blue color we see is blue light waves scattered down toward us from the white sunlight passing through the air overhead • At night, the sun is tangent to the Earth. The light’s path is longer, so the short-wavelength light gets scattered out, leaving the colour red which has a longer wavelength.