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 determine the effect of tripling the wavelength of incident photons on current flow, we need to consider the relationship between wavelength, energy, and the stopping potential.
The energy of a photon is given by the equation E = hc/λ, where E is the energy, h is Planck's constant (4.135667696 x 10^-15 eV*s), c is the speed of light (2.998 x 10^8 m/s), and λ is the wavelength.
Given that the initial energy of the photons is 12 eV, we can find the corresponding wavelength using the equation:
12 eV = (4.135667696 x 10^-15 eV*s * 2.998 x 10^8 m/s) / λ
Solving for λ, we find the initial wavelength to be approximately 104 nm.
Now, if we triple the wavelength to find the new value, we calculate:
λ' = 3 * 104 nm = 312 nm
Using this new wavelength, we can find the corresponding energy:
E' = (4.135667696 x 10^-15 eV*s * 2.998 x 10^8 m/s) / 312 nm
Solving for E', we find the new energy to be approximately 1.26 eV.
Comparing the new energy (1.26 eV) to the stopping potential (8.0 V), we see that the energy is still greater than the stopping potential. Therefore, there will still be current flow when the wavelength is tripled.
So, in conclusion, if the wavelength of the incident photons is tripled, the energy of the photons would decrease to approximately 1.26 eV. It is important to note that the stopping potential remains the same, and as long as the energy of the photons is greater than the stopping potential, current will still flow from the metal.