Photoelectric Experiment

Question 1

Experimental Observations of The Photoelectric experiment

Answer 1

1) The Maximum Kinetic energy of the emitted electrons depends only on the FREQUENCY of the light, NOT the INTENSITY

2) If the FREQUENCY is ABOVE THE threshold frequency, photoelectrons are emitted almost immediately, regardless of light intensity

3) If the frequency is BELOW the threshold frequency, no electrons are emitted, regardless of light intensity

4) The Maximum Kinetic Energy increases with increasing frequency

Question 2

What is the Work Function?

Answer 2

The MINIMUM energy required to release photoelectrons from the metal surface

Question 3

What is Threshold Frequency?

Answer 3

The minimum FREQUENCY of light required to release photoelectrons from a metal surface

Question 4

What is the Stopping Voltage (Vs)

Answer 4

Minimum voltage required to stop the maximum kinetic energy of emitted electrons

Question 5

What does the Wave Model predict for the experimental observation?

Answer 5

1) Maximum KE of electrons is dependent on light intensity:

The wave model says that as light intensity increases, energy should be transferred into the metal at a faster rate, therefore electrons should be ejected with more Kinetic energy. Contradicts with experimental result.

2) There should be a reasonable time interval between the incidence of light and the ejection of photoelectrons

The wave model says that this measureable time interval is required so that the electron can absorb the incident radiation before it acquires enough energy to be ejected from the metal. However, this contradicts with the experimental result as electrons are ejected almost instantaneously. (without time delay)

3) The wave model predicts that electrons should be emitted at ANY light frequency, as long as the light INTENSITY is high, because energy is transferred to the metal regardless of frequency. Contradicts with experimental result.

4) The wave model predicts that there should be NO relationship between freqency of light and the maximum kinetic energy of emitted electrons, and that it should be related to the INTENSITY instead.