Correct Answer - Option 2 : Frequency of incident light is greater than threshold frequency
The correct answer is option 2) i.e. Frequency of incident light is greater than the threshold frequency
CONCEPT:
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Photoelectric effect: The photoelectric effect is a phenomenon where electrons are ejected from a metal surface when the light of sufficient frequency is incident on it.
- When a photon falls on the metal surface, the photon’s energy is transferred to the electron.
- Some part of the energy gets utilized in removing the electron from the metal surface, and the remaining goes into giving kinetic energy for the ejected electron.
Therefore, the total energy of photon = work function + maximum kinetic energy of the electron.
- The energy of a photon is given by the equation:
\(E =hν\)
Where ν is the frequency of incident light and h is the Planck's constant.
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Work function: It is the minimum amount of energy required to cause photo-emission of electrons from a metal surface when light is incident on it.
- The work function is also known as the threshold energy.
EXPLANATION:
- The photoelectric effect is said to have occurred when an electron is ejected from the metal surface with light incident on it.
- For an electron to be emitted, it must acquire energy large enough to leave the metal surface. For this to happen, the electron should have an energy greater than the threshold energy.
- Since energy is directly proportional to frequency, the electron must acquire a frequency greater than the threshold frequency.
- Therefore, the frequency of incident light has to be greater than the threshold frequency for the photoelectric effect to occur.
