Light as a wave and as a particle
Grade 11 Science Worksheet
Circle the best answer, or write your answer on the line.
Light of 7.5 × 10¹⁴ Hz falls on cesium (work function 2.1 eV). With h = 4.135667696 × 10⁻¹⁵ eV·s, what is the electrons' greatest kinetic energy, to 0.01 eV, Ari?
Light of 10 × 10¹⁴ Hz falls on potassium (work function 2.3 eV). With h = 4.135667696 × 10⁻¹⁵ eV·s, what is the electrons' greatest kinetic energy, to 0.01 eV, Bo?
Light of 15 × 10¹⁴ Hz falls on zinc (work function 4.3 eV). With h = 4.135667696 × 10⁻¹⁵ eV·s, what is the electrons' greatest kinetic energy, to 0.01 eV, Esme?
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Work functions of some metals (HyperPhysics, from the CRC Handbook)
Metal Work function (eV) cesium 2.1 sodium 2.28 potassium 2.3 calcium 2.9 zinc 4.3 copper 4.7 Using the table, which metal gives up electrons to the lowest-energy photons, Jun?
- Zinc
- Cesium
- Copper
Using the table, 2.48 eV green photons shine on each metal. How many metals give up electrons, Kira?
- 6
- 1
- 3
Using the table, why does visible light free no electrons from copper, Luz?
- Copper reflects the light back
- Visible light is too bright
- Its photons carry less than 4.7 eV
Very bright red light shines on zinc, but no electrons come out. Why, Milo?
- The light needs to be even brighter
- Zinc has no electrons
- Each red photon has too little energy
Dim ultraviolet light shines on zinc. When do the first electrons leave, Pia?
- After the metal warms up
- Not until the light is brighter
- Almost at once
In the photon diagram, the n = 3 to n = 2 photon carries 1.89 eV. About what wavelength is it, Ren?
- About 656 nm, red
- About 2343 nm, infrared
- About 122 nm, ultraviolet
In the photon diagram, can hydrogen at n = 1 absorb a 5 eV photon, Zee?
Use the picture in question 9.
- Yes: any photon can be absorbed
- No: 5 eV matches no gap
- Yes: it moves halfway to n = 2