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?
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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, 2.48 eV green photons shine on each metal. How many metals give up electrons, Kira?
- 6
- 3
- 1
Using the table, why does visible light free no electrons from copper, Luz?
- Visible light is too bright
- Copper reflects the light back
- Its photons carry less than 4.7 eV
Very bright red light shines on zinc, but no electrons come out. Why, Milo?
- Each red photon has too little energy
- Zinc has no electrons
- The light needs to be even brighter
Ultraviolet light already frees electrons from zinc. It is made brighter. What changes, Noah?
- Each electron leaves with more energy
- No electrons leave
- More electrons leave each second
Dim ultraviolet light shines on zinc. When do the first electrons leave, Pia?
- Not until the light is brighter
- Almost at once
- After the metal warms up
In the photon diagram, the n = 3 to n = 2 photon carries 1.89 eV. About what wavelength is it, Ren?
- About 2343 nm, infrared
- About 656 nm, red
- About 122 nm, ultraviolet
In the photon diagram, what energy would a photon from a drop straight from n = 3 to n = 1 carry, Tala?
Use the picture in question 8.
- 15.11 eV
- 12.09 eV
- 1.89 eV
In the photon diagram, can hydrogen at n = 1 absorb a 5 eV photon, Zee?
Use the picture in question 8.
- Yes: any photon can be absorbed
- No: 5 eV matches no gap
- Yes: it moves halfway to n = 2