Photons of energy 12eV are incident on a metal. It is found that current flows from the metal until a stopping potential of 8.0V is applied.

What would happen if the wavelength of the incident photons was tripled?

Would the energy be 4eV,so 12/3=4, and there will be no current flow? Is this correct? Please help!Thank you.

To understand what would happen if the wavelength of the incident photons was tripled, we need to consider the basic principle of the photoelectric effect.

The photoelectric effect states that when light (photons) of sufficient energy is incident on a metal surface, electrons can be emitted. The minimum energy required to liberate an electron from the metal is called the work function (ϕ) of the metal.

In the given scenario, photons of energy 12eV are incident on the metal, and a stopping potential of 8.0V is required to stop the flow of current. This means that the energy of the incident photons is larger than the work function.

Now, if the wavelength of the incident photons is tripled, the energy of each photon would decrease. This can be understood using the equation:

E = hc/λ

Where:
E = energy of a photon
h = Planck's constant
c = speed of light
λ = wavelength of light

If the wavelength triples, the energy of each photon is reduced to one-third of its original value.

Therefore, the new energy of each photon would be (12eV / 3) = 4eV.

Now, if the energy of each photon is reduced to 4eV, it might not be sufficient to overcome the work function of the metal. In this case, electrons would not be emitted, and no current would flow.

So, you are correct in thinking that if the wavelength of the incident photons is tripled, the new energy would be 4eV, and there might be no current flow.

It's worth noting that the photoelectric effect depends on the energy of the photons, not their frequency or wavelength. Changing the wavelength affects the energy carried by each photon, which in turn determines if electron emission is possible or not.

I hope this explanation helps! Let me know if you have any further questions.