I've got this question wrong 2 times now...
Which of the following statements about the photoelectric effect are correct?
I. If electrons are being ejected, the number of electrons ejected increases with increasing light intensity.
II. The minimum energy required for electron ejection varies for different metals.
III. Electron ejection is independent of both the time the light shines on the metal and the intensity of the light.
http://www.physlink.com/education/askexperts/ae24.cfm
To determine which of the statements about the photoelectric effect are correct, let's analyze each option one by one:
I. If electrons are being ejected, the number of electrons ejected increases with increasing light intensity.
This statement is correct. According to the photoelectric effect, the number of electrons ejected from a metal surface increases with the intensity of the incident light. The greater the intensity of light, the more energy is transferred to the electrons, increasing the likelihood of their ejection.
II. The minimum energy required for electron ejection varies for different metals.
This statement is also correct. The minimum energy required to eject an electron from a metal surface, known as the work function, depends on the specific metal. Each metal has a unique work function, which is the amount of energy required to overcome the attractive forces holding the electrons within the metal and allow them to be liberated.
III. Electron ejection is independent of both the time the light shines on the metal and the intensity of the light.
This statement is incorrect. Electron ejection is dependent on both the time the light shines on the metal and the intensity of the light. The longer the light shines on the metal and the higher the intensity, the greater the number of electrons ejected.
Therefore, the correct statements about the photoelectric effect are I and II.