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?
- Cesium
- Zinc
- Copper
Using the table, 2.48 eV green photons shine on each metal. How many metals give up electrons, Kira?
- 1
- 6
- 3
Using the table, why does visible light free no electrons from copper, Luz?
- Its photons carry less than 4.7 eV
- Copper reflects the light back
- Visible light is too bright
Very bright red light shines on zinc, but no electrons come out. Why, Milo?
- The light needs to be even brighter
- Each red photon has too little energy
- Zinc has no electrons
Dim ultraviolet light shines on zinc. When do the first electrons leave, Pia?
- Not until the light is brighter
- After the metal warms up
- Almost at once
In the photon diagram, what energy would a photon from a drop straight from n = 3 to n = 1 carry, Tala?
- 12.09 eV
- 15.11 eV
- 1.89 eV
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
- Yes: it moves halfway to n = 2
- No: 5 eV matches no gap