Light as a wave and as a particle

Answer Key - Grade 11 Science Worksheet - Challenge Me

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

1. 1.

   The CRC Handbook gives sodium a work function of 2.28 eV. With hc = 1239.84 eV·nm, what is the longest wavelength that frees electrons, to 0.1 nm, Bo?

   543.8 nm
2. 2.

   The CRC Handbook gives magnesium a work function of 3.68 eV. With hc = 1239.84 eV·nm, what is the longest wavelength that frees electrons, to 0.1 nm, Esme?

   336.9 nm
3. 3.

   Very dim light sends photons through two slits one at a time. What builds up on the screen over time, Kira?

   • The same bright and dark bands
   • An even glow
   • Two plain bright lines
4. 4.

   One of the two slits is covered. What happens to the bands, Luz?

   • They get sharper
   • They double in number
   • The bands go away
5. 5.

   Milo says bright enough red light will free electrons from any metal. Agree or disagree?

   • Agree: brightness adds energy to each photon
   • Agree: bright light works on any metal
   • Disagree: red photons may be too weak
6. 6.

   Noah says doubling the brightness of light on cesium doubles each electron's greatest energy. Agree or disagree?

   • Disagree: it doubles the number of electrons
   • Agree: energy doubles with brightness
   • Agree: brighter light gives faster electrons
7. 7.

   Pia says the photoelectric effect proves light is never a wave. Agree or disagree?

   • Agree: particles can't interfere
   • Disagree: light also shows wave interference
   • Agree: waves can't free electrons
8. 8.

   Ultraviolet light of 250 nm shines on copper (work function 4.7 eV). Are electrons freed, Ren?

   • No: copper can't free electrons
   • No: 250 nm is too long
   • Yes: each carries about 4.96 eV
9. 9.

   Light of 300 nm and light of 600 nm are compared. How do their photon energies compare, Tala?

   • The 300 nm photons carry twice as much
   • They are equal
   • The 600 nm photons carry twice as much
10. 10.

    Infrared photons of about 1 eV shine on cesium (2.1 eV). What happens, Zee?

    • Electrons leave with 3.1 eV
    • Electrons leave with 1.1 eV
    • No electrons are freed