The Electromagnetic Spectrum · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

The Electromagnetic Spectrum

Science · Waves, Light & Sound · ages 12-13
Name ______________________   Date ____________

  1. Which region of the electromagnetic spectrum do doctors use to take pictures of bones inside your body?

    • X-rays
    • radio waves
    • infrared
    • microwaves

  2. Which list shows the electromagnetic spectrum in order of increasing frequency?

    • radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays
    • gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves
    • radio waves, visible light, microwaves, infrared, ultraviolet, gamma rays, X-rays
    • visible light, infrared, radio waves, microwaves, X-rays, ultraviolet, gamma rays

  3. Radio waves and X-rays travel at the same speed in a vacuum.

    Circle one:   True   False

  4. How does an X-ray's speed through empty space compare with a radio wave's speed?

    • The X-ray travels faster
    • They travel at exactly the same speed
    • The radio wave travels faster

  5. Which type of wave has a longer wavelength than visible light?

    • infrared
    • ultraviolet
    • X-rays
    • gamma rays

  6. Why are gamma rays more dangerous to living things than visible light?

    • They have a much higher frequency, so each wave carries enough energy to damage cells
    • They travel faster than visible light
    • They have longer wavelengths than visible light
    • They are brighter than visible light

  7. Which pair correctly matches a region of the spectrum with one of its uses?

    • Microwaves - cooking food
    • Gamma rays - broadcasting radio shows
    • Visible light - sterilizing hospital equipment

  8. Which of these is a real hazard of ultraviolet (UV) waves?

    • They can cause sunburn and damage skin
    • They make food go cold
    • They block all radio signals
    • They have no effect on the human body

  9. A microwave oven uses waves with a frequency of 2.5 GHz (2,500,000,000 Hz). What is the wavelength of these waves in meters?

    Answer: ______________

  10. Leo says microwaves must be more dangerous than ultraviolet light because a microwave oven heats food so quickly. What's wrong with his reasoning?

    • He's right, microwaves carry more energy than UV
    • He's wrong: UV has a higher frequency and more energy per wave, even though microwaves heat food quickly
    • He's wrong: microwaves and UV carry exactly the same energy
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Answer key

For grown-ups. Fold this page away before handing over the rest.

The Electromagnetic Spectrum W1-mt_XSp-S0wter-s1

  1. X-rays · X-rays pass through soft tissue but are absorbed by bone, so they make shadow pictures of your skeleton. Doctors limit the dose because X-rays can also damage living cells.
  2. radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays · Frequency climbs steadily from radio waves at the low end up to gamma rays at the high end. Visible light sits in the middle.
  3. True · True. In a vacuum, every electromagnetic wave moves at 3 × 10⁸ m/s, no matter its frequency or wavelength.
  4. They travel at exactly the same speed · Every type of electromagnetic wave moves at 3 x 10^8 m/s in a vacuum. Only frequency and energy differ.
  5. infrared · Lower frequency means longer wavelength. Infrared has a lower frequency than visible light, so its waves are longer. UV, X-rays, and gamma rays all have shorter wavelengths than visible light.
  6. They have a much higher frequency, so each wave carries enough energy to damage cells · Gamma rays have extremely high frequencies, and high frequency means high energy. That energy can break apart molecules inside living cells, which makes them dangerous.
  7. Microwaves - cooking food · Microwaves heat food by shaking water molecules. Radio broadcasting uses radio waves, and sterilizing equipment usually uses UV or gamma rays.
  8. They can cause sunburn and damage skin · UV waves carry enough energy to harm skin cells, causing sunburn and raising the risk of skin cancer. They are also useful, for example for sterilizing medical tools.
  9. 0.12 · Wavelength = 3 × 10⁸ ÷ 2.5 × 10⁹ = 0.12 meters, which is 12 centimeters, about the length of a pencil.
  10. He's wrong: UV has a higher frequency and more energy per wave, even though microwaves heat food quickly · Heating speed depends on the power of the oven, not just the wave type. UV sits higher on the spectrum than microwaves, so each UV wave carries more energy and can damage cells microwaves can't.
Worksheet · LightMySky