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Question
What is the effect of threshold frequency and stopping potential on increasing the frequency of the incident beam of light? Justify your answer.
Solution
Threshold frequency: The threshold frequency is the lowest frequency of incident radiation that can cause an electron to be ejected from a metal. At frequencies below the threshold, there is no photoelectric emission.
The frequency of light that will produce an emission of electrons from the metal's surface is referred to as the threshold frequency.
If ν signifies the frequency of the incident photon and νth signifies threshold frequency, then;
- If ν < νth, then this denotes that no ejection of photoelectrons will occur.
- If ν = νth, then this denotes that photoelectrons are just ejected from the surface of the metal, however, the kinetic energy of the electron is equal to zero.
The minimal negative voltage that must be provided to the anode to halt the photocurrent is known as stopping potential. When expressed in electron volts, the stopping voltage corresponds to the electrons' maximum kinetic energy.
Stopping potential, `eV_0 = hν_"incident" - phi`
Where ν is the frequency of the incident radiation and Φ is the metal surface's work function. As a result, stopping potential rises as incident radiation frequency rises.
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