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11th grade The electromagnetic spectrum and its uses worksheet

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The electromagnetic spectrum and its uses

Grade 11 Science Worksheet

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Circle the best answer, or write your answer on the line.

  1. A germicidal lamp gives off 254 nm photons. With hc = 1,240 eV·nm, what is each photon's energy in eV, Ari?

  2. A red LED gives off 620 nm photons. With hc = 1,240 eV·nm, what is each photon's energy in eV, Bo?

  3. A lab X-ray source gives off 0.124 nm photons. With hc = 1,240 eV·nm, what is each photon's energy in eV, Esme?

  5. Using the device table, which wave has the longest wavelength, and about how long is it, Jun?

    • Microwave oven, about 12 cm, since GHz is the biggest unit
    • FM radio, about 0.33 m
    • FM radio, about 3.1 km
    • FM radio, about 3.1 m

  6. Using the device table, which wave has the highest photon energy, and why, Kira?

    Use the picture in question 4.

    • The germicidal lamp: 254 nm is the shortest wavelength
    • The TV remote, since 940 is the biggest number
    • FM radio, since the longest waves carry the most energy
    • The microwave oven, since 2.45 GHz is a big number

  7. A building is 20 m wide. Using the device table, which wave bends (diffracts) most around it, Luz?

    Use the picture in question 4.

    • The TV remote, since infrared goes around corners
    • Wi-Fi, since it passes through walls instead of bending
    • The germicidal lamp, since higher-energy waves bend more
    • FM radio: its 3 m wavelength is closest to the building's size

  8. A microwave oven runs at 2.45 GHz. What are its wavelength and the spacing of hot spots (half a wavelength), Milo?

    • Wavelength 12.2 cm; hot spots 12.2 cm apart, one wavelength
    • Wavelength 12.2 cm; hot spots about 6.1 cm apart
    • Wavelength 6.1 cm; hot spots 3.1 cm apart
    • Wavelength 12.2 m; hot spots about 6.1 m apart

  9. Water absorbs 4.19 J per gram per °C. An oven puts 700 W into 250 g of water for 60 s. What is the temperature rise, Pia?

    • About 40 °C
    • About 0.67 °C, leaving out the time
    • About 40,000 °C, using 0.25 kg with joules per gram
    • About 80 °C, doubling the power

  10. Ren compares two 1.0 m telescopes: one sees 500 nm light, one sees 21 cm radio waves. Which resolves finer detail, and by what factor?

    • The optical one, about 420,000 times finer
    • Neither: both have a 1.0 m diameter
    • The optical one, about 42 times finer
    • The radio one, since longer waves reach farther

  11. The James Webb telescope observes infrared. Why does that help it see the most distant galaxies, Zee?

    • Distant galaxies give off infrared light and nothing else
    • Infrared photons carry more energy, so they travel farther
    • Cosmic expansion stretches their light into the infrared
    • Infrared is the one kind of light that crosses space
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11th grade The electromagnetic spectrum and its uses worksheet – printable
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About this worksheet

The electromagnetic spectrum and its uses. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can order the spectrum by frequency, wavelength and photon energy, and find wavelengths from λ = c ÷ f with kHz, MHz and GHz.
  • I can find photon energy from E = hc ÷ λ (hc ≈ 1,240 eV·nm) and compare bands by E = hf.
  • I can explain uses with wave ideas: why mesh blocks microwaves but not light, why long waves diffract round buildings, why shorter waves resolve finer detail, why skin glows in infrared (Wien's law), and why telescopes go to orbit.
  • I can find signal times (Moon, L1, geostationary satellite) counting every leg, and judge claims such as "microwaves cook from the inside" or "the air absorbs blue light".

Standard: supports HS-PS4-5

Words to know

frequency f, wavelength λ: Waves per second; length of one wave, with c = fλ

photon: One packet of light, with energy E = hf

electronvolt (eV): A small unit of energy used for photons

diffraction: Waves bending around an obstacle or through a gap

Wien's law: A warm object's glow peaks at λ = 2.898 × 10⁻³ m·K ÷ T

Common mistakes

Your child used the frequency number without its prefix. MHz, GHz and kHz must become hertz before dividing into c.

Your child divided the wrong way round. The wavelength is c ÷ f, and the energy is hc ÷ λ.

Your child multiplied by hc. Energy goes down as wavelength goes up, so divide hc by λ.

Questions parents ask

What is the most common mistake with the electromagnetic spectrum and its uses?

Your child used the frequency number without its prefix. MHz, GHz and kHz must become hertz before dividing into c.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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