A metallic surface emits photo electrons when green light falls on it. But the metal does not emit when yellow light falls on it. Which of the following is correct when red light falls on the metallic surface?
Choose one answer.
a. The number of photoelectrons will be more.
b. The number of photoelectrons will be less.
c. The number of photoelectrons will be the same.
d. There is no emission of photoelectrons.
the number of photoelectrons will be less
To determine the correct answer, we need to understand the phenomenon known as the photoelectric effect. The photoelectric effect occurs when photons (particles of light) strike a metallic surface and eject electrons from the metal, creating photoelectrons. However, for this effect to occur, the energy of the photons must be sufficient to overcome the binding energy of the electrons in the metal.
In this case, the metallic surface emits photoelectrons when green light falls on it but not when yellow light falls on it. This suggests that the energy of the green light photons is sufficient to overcome the binding energy of the electrons, while the energy of the yellow light photons is not enough.
Now, when red light falls on the metallic surface, we need to consider the energy of red light photons. Red light has a lower energy than green light, which means its photons have less energy. Based on this information, we can determine the correct answer.
Since red light has lower energy than green light, it is expected that the red light photons will have even less energy to overcome the binding energy of the electrons in the metal. Therefore, the correct answer is:
b. The number of photoelectrons will be less.
When red light falls on the metallic surface, the number of photoelectrons emitted will be less compared to the emission caused by green light.