Sodium surface is illuminated by ultraviolet and visible radiation successively and the stopping potential determined. The stopping potential isa)Greater with visible lightb)Equal in both casesc)Greater with ultraviolet lightd)Infinite in both casesCorrect answer is 'C'. Can you explain this answer?

Question

Answer

Answer

I think answer is A because stopping potential ∝ wavelength λ(visible) greater than λ(UV)

Answer

Explanation:

When light falls on a metal surface, it causes the emission of electrons from the surface. This phenomenon is known as the photoelectric effect. The energy required to remove an electron from a metal surface is called the work function. The energy of a photon is given by E = hf, where E is the energy, h is Planck's constant, and f is the frequency of the light.

Stopping Potential:

The stopping potential is the minimum potential difference required to stop the emitted electrons from reaching the other electrode. It depends on the energy of the incident photons and the work function of the metal surface.

Effect of Ultraviolet Light:

Ultraviolet (UV) light has a higher frequency and higher energy compared to visible light. When UV light falls on the sodium surface, the energy of the photons is sufficient to overcome the work function of sodium and eject electrons. The high energy of UV light results in the emission of electrons with greater kinetic energy. This means that a higher potential difference is required to stop these high-energy electrons from reaching the other electrode. Therefore, the stopping potential is greater with ultraviolet light.

Effect of Visible Light:

Visible light has a lower frequency and lower energy compared to UV light. When visible light falls on the sodium surface, the energy of the photons may not be sufficient to overcome the work function of sodium. As a result, no electrons are emitted, and the stopping potential is zero.

Comparison:

Comparing the stopping potential with ultraviolet and visible light:
- Ultraviolet Light: The stopping potential is greater because the energy of the incident photons is sufficient to overcome the work function of sodium and eject electrons.
- Visible Light: The stopping potential is zero because the energy of the incident photons is not sufficient to overcome the work function of sodium.

Therefore, the correct answer is option 'C' - The stopping potential is greater with ultraviolet light.

Answer

UV rays found in Lyman series and visible ray found in Balmar series

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