Evans SPH 4U1

Physics Grade 12

Quantum Review:

 

Textbook Self-quiz page 659

  True/False #1-11

  Multiple Choice #12-15, 18-24

 

Some Textbook Questions page 661

#3-10, 13, 18, 22, 26, 29

 

More Questions:

 

1)      Describe what effect, if any, the following changes have on the maximum kinetic energy of the emitted electrons

a.       Frequency of radiation is unchanged but the intensity is increased.

(If the threshold frequency has not been reached then no electrons will be eimitted and there will be no current flow. If the threshold frequency has been reached then the energy will remain the same but the current flow will increase and there will be more photoelectrons. Each individual photoelectron will not have andy more energy than it had before you increased the intensity.)

b.      Intensity of radiation is kept constant but the frequency is increased.

(As you increase the frequency, you will increase the energy of the photoelectron being emitted)

 

2)      Calculate the energy of a single photon in each of the following cases:

a.       Radiation of frequency 4.0 x 10 14 Hz (2.65 x 10 -19 Joules)

b.      Radiation of wavelength 500 nm. (3.98 x 10 -19 Joules)

 

3)      Calculate the threshold frequency and the threshold wavelength for a phot-emissive metal of work function equal to 2.2 eV. (5.3 x 10 14 Hz)

 

4)      The work functions for some common metals are given below:

      Silver                4.65 eV

      Gold                 5.37 eV

      Copper             4.65 eV

      Platinum           5.65 eV

      Calculate the threshold frequency for each metal.

 

5)      Find the value of the longest wavelength of electromagnetic radiation that could cause electron emission from platinum surface with W = 5.65 eV

 

6)      With what speed would an electron be ejected from sodium that has a work function of 2.36 eV when it is illuminated b y a 442 nm light. (3.98 x 10 -5 m/s)

 

7)      Briefly describe why the classical wave theory was replaced in a bid to explain the photoelectric effect. (See textbook and explain about discrete energy levels that were found and the photoelectric experiment)

 

8)      Outline the main points in Einsteinís explanation of the photoelectric effect. (see class notes and text to explain the photoelectric experiment)