1. Which of the following describes the dual nature of light? 1. Light has a frequency and a wavelength. 2. Light behaves as particle and as wave. 3. Light travels through air and through vacuum. 4. Light can has two states: on and off.

2. The ejection of electrons from a metal surface when the surface is hit by a photon whose energy is higher than the metal’s work function is called ______________. 1. Photoelectric effect 2. Compton effect 3. Zeeman effect 4. Tyndall effect

3. What happens when the intensity of light, whose energy is higher than the work function of the metal, is increased? 1. The ejected electrons move faster. 2. The ejected electrons move slower. 3. More electrons are ejected. 4. Less electrons are ejected.

4. What is the effect of increasing the frequency of light that is striking the metal surface? 1. The ejected electrons move faster. 2. The ejected electrons move slower. 3. More electrons are ejected. 4. Less electrons are ejected.

5. When will certain color of light be able to eject electrons from a metal surface? 1. When it strikes the metal in bursts. 2. When it shines on the metal for a long time. 3. When its energy is higher than the work function of the metal. 4. When it hits the metal surface perpendicularly.

6. The threshold frequency of sodium is 4.4 x 10 14 Hz. What is the work function of sodium? 1. 8.5 x 10 -19 J 2. 6.7 x 10 -19 J 3. 4.3 x 10 -19 J 4. 2.9 x 10 -19 J

8.  It behaves as a wave and as a particle.  The particle of light is called a photon.

9.  The emission of electrons from a metal surface when light of certain frequency strikes the surface.  It was first explained by Albert Einstein and he was awarded the Nobel prize in 1921 for his work on this phenomenon.

10. As the intensity of the light increases, more electrons are ejected from the surface of sodium. Intense light source means more photons are hitting the metal surface. Each photon is capable of ejecting an electron.

11. Different colors of light will cause the electrons to be ejected at different speeds.

14. Frequency increasing

15. Red light photons therefore than violet light photons and even less than UV photons

19. 1. The threshold wavelength of zinc is 310 nm. a. Find the threshold frequency of zinc. b. What is the work function in eV of zinc. 2. The work function for cesium is 1.96 eV. a. What is its threshold wavelength? b. What is its threshold frequency?

20. 3. The threshold frequency of sodium is 4.4 x 10 14 Hz. How much work must be done to free an electron from the surface of sodium? 3. Barium has a work function of 2.48 eV. What is the longest wavelength of light that will cause electrons to be emitted from barium? 3. The threshold frequency of tin is 1.2 x 10 15 Hz. a. What is the threshold wavelength? b. What is the work function of tin?

21. Which of the following describes the dual nature of light? 1. Light has a frequency and a wavelength. 2. Light behaves as particle and as wave. 3. Light travels through air and through vacuum. 4. Light can have two states: on and off.

22. The ejection of electrons from a metal surface when the surface is hit by a photon whose energy is higher than the metal’s work function is called ______________. 1. Photoelectric effect 2. Compton effect 3. Zeeman effect 4. Tyndall effect

23. What happens when the intensity of light, whose energy is higher than the work function of the metal, is increased? 1. The ejected electrons move faster. 2. The ejected electrons move slower. 3. More electrons are ejected. 4. Less electrons are ejected.

24. What is the effect of increasing the frequency of light that is striking the metal surface? 1. The ejected electrons move faster. 2. The ejected electrons move slower. 3. More electrons are ejected. 4. Less electrons are ejected.

25. When will certain color of light be able to eject electrons from a metal surface? 1. When it strikes the metal in bursts. 2. When it shines on the metal for a long time. 3. When its energy is higher than the work function of the metal. 4. When it hits the metal surface perpendicularly.

26. The threshold frequency of sodium is 4.4 x 10 14 Hz. What is the work function of sodium? 1. 8.5 x 10 -19 J 2. 6.7 x 10 -19 J 3. 4.3 x 10 -19 J 4. 2.9 x 10 -19 J