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BE2C1 PARTICLE NATURE OF LIGHT
1.1 THE PUZZLING PHOTOELECTRIC EFFECT
1.1 THE PUZZLING PHOTOELECTRIC EFFECT
Brief INTRO
Chapter 1.1a
Chapter 1.1b
Chapter 1.1c
1.2 EINSTEIN's INTERPRETATION OF THE PHOTOELECTRIC EFFECT
1.2 EINSTEIN's INTERPRETATION OF THE PHOTOELECTRIC EFFECT
Chapter 1.2a
Chapter 1.2b
Chapter 1.2c
Chapter 1.2d
Summary
Revision Exercise
1.1 Rutherford's model and scattering experiments
1.1 Rutherford's model and scattering experiments
Preparation - Chapter 1.1a, Chapter 1.1b
Participation - Assignment P.8 Q7-10 and P.41 Q26, 30
Presentation - Blackboard, Student's Work
Possession
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1.1a
1.1b
1.2 The puzzling photoelectric effect
1.2 The puzzling photoelectric effect
Preparation - Chapter 1.2a, b, b2 , c, c2(Threshold frequency), c3(no time delay), c4(I-V relationship), c5 (example 1), c6 (Intensity of light), c7 (Failure of wave theory)
Participation - Assignment P.18 Q6, 8 and P.41 Q22, 27
Presentation - Blackboard, Student's Work
Possession
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Neon Bulb - Red, Green and Blue light
An Introduction
Electroscope and Photoelectric Current
Threshold Frequency
No time delay
I-V relationship
Example 1
Intensity of light
Failure of wave theory
1.3 Eintein's interpretation of the photoelectric effect
1.3 Eintein's interpretation of the photoelectric effect
Preparation - Chapter 1.3a, Chapter 1.3b, Chapter 1.3c
Participation -
Assignment 3A
P.33 Q10-14 and P.41 Q23, 24, 28, 29, 25
Assignment 3B
P.41 Q31-39Presentation - Blackboard, Student's Work
Possession
> ...
1.3a
1.3b
1.3c
Check if you know THESE ...
Check if you know THESE ...
What wave theory assumes? And why it cannot explain photoelectric effect?
According to wave theory, wave is a continuous form of energy, its energy is determined by its amplitude only (but not frequency).
According to wave theory, an electron can ALWAYS absorb enough energy to escape from a metal surface if ENOUGH time is given. However, it is not the case. The incident wave must have a HIGH ENOUGH FREQUENCY and it takes NO TIME to have an electron to emit.
According to photon theory, light is wave packet.
An electron may absorb a photon in no time. If the energy of photon (E = hf) is high enough, the photon is absorbed and the electron is emitted. However, an electron can only absorb one photon only.LASTLY, the maximum KE of photoelectron is limited in photoelectric effect experiment as Kmax = hf-W (W is work function of the metal surface). In wave theory, however, Kmax should increase with intensity (or amplitude) of the wave, and of course, wave theory is wrong.
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