1. Suppose Richard was working with light matter interaction. He arranged an experimental setup just as the figure below Light Detector Metal surface Electrons Ammeter Vacuum chamber 州ー Battery (a)When light of 650nm wavelength fell on copper metallic surface there was no reading on the ammeter. After that when he changed aluminum with copper. Suddenl he started see reading on the ammeter. Explain this phenomena? (b) As he increased the reverse voltage by the battery then again current reading became zero. Why did this happen? (c) If work function of aluminum is 4.4eV. Find what is minimum wavelength of light required to generate photocurrent.

1. Suppose Richard was working with light matter interaction. He arranged an experimental setup just as the figure below Light Detector Metal surface Electrons Ammeter Vacuum chamber 州ー Battery (a)When light of 650nm wavelength fell on copper metallic surface there was no reading on the ammeter. After that when he changed aluminum with copper. Suddenl he started see reading on the ammeter. Explain this phenomena? (b) As he increased the reverse voltage by the battery then again current reading became zero. Why did this happen? (c) If work function of aluminum is 4.4eV. Find what is minimum wavelength of light required to generate photocurrent.