## Photons

$c=\lambda v$

Tara_Hekmati_3B
Posts: 28
Joined: Wed Sep 21, 2016 2:59 pm

### Photons

So I understand that the intensity of energy is related to the number of photons present, but then why does the energy equation consider frequency (E=vh)?

Theresa Dinh 3F
Posts: 26
Joined: Fri Jul 22, 2016 3:00 am

### Re: Photons

I believe that it is because the higher the frequency the stronger it is. For example a radio wave, which has a low frequency rate, is weaker than a gamma ray, which has a high frequency (due to shorter wavelength).

Tara_Hekmati_3B
Posts: 28
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Photons

OK thanks, so there's no colorations between the photons and the frequency, right? because one looks at light on a smaller scale and the other is on a bigger scale.

Joseph Nguyen 3L
Posts: 24
Joined: Fri Jul 22, 2016 3:00 am

### Re: Photons

Tara_Hekmati_1G wrote:So I understand that the intensity of energy is related to the number of photons present, but then why does the energy equation consider frequency (E=vh)?

Energy is NOT intensity. Going back to the photoelectric effect, increasing the INTENSITY (or the number of photons present), will NOT increase energy and therefore no electrons will be ejected. If FREQUENCY increases, according to E = hv, then ENERGY increases. Think of the energy as potential and kinetic energy of ONE photon, (E = 1/2MV^2) dependent on the velocity and mass of the electron. The INTENSITY is how many photons there are, but that will not change any velocity to increase energy.

Janice Kim 3I
Posts: 33
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Photons

The shorter the wavelength, the higher the frequency. Shorter wavelengths mean increased energy for each photon in a beam of light. In order to reach the threshold of energy to eject electrons from the metal, the photons must have enough energy. If the photons in a beam of light do not have enough energy, it does not matter how many photons there are. Increasing the intensity will only increase the number of photons, not the energy of each photon. So the frequency comes into play when scientists use light of shorter wavelengths (higher frequency) to match the energy of the photon to the energy needed to remove the electron.