Light Intensity

[ngarcia]

Just to clarify, increasing light intensity increases the number of photons. And, if, and only if, the energy per photon is greater/equal to the energy needed to remove an electron, then increasing light intensity results in more ejected electrons. However, one cannot assume that electrons are being emitted with high intensity light alone. Do I have a correct understanding?

[Ronak Naik]

Yes, that is exactly correct. The intensity of light is directly related to the number of photons not the common mistake of thinking about energy. Once enough energy from the photon has been put in, the electron will be ejected with a kinetic energy of 1/2mv^2. Each photon will eject one electron if the photon has greater energy than the required work energy.

[Amanda Ung 4D]

Sounds good! Remember to consider light as photons, or packets of energy where one photon interacts with one electron. High intensity light with long wavelengths and low frequency wouldn't be able to eject electrons; therefore, it really depends on the energy of the photon and not the intensity of the light. That is what I took from the lecture.

[chari_maya 3B]

One thinking point in the texbook asked why ultraviolet radiation is much more harmful to living tissue than infared radiation... I was wondnerinf if someone could explain the answer.

[Alexandra Bartolome 2H]

One thinking point in the texbook asked why ultraviolet radiation is much more harmful to living tissue than infared radiation... I was wondnerinf if someone could explain the answer.

I think this is because ultraviolet radiation has higher frequency and shorter wavelengths than infrared radiation, which means it has more energy to penetrate our skin and do damage.

[faithkim1L]

Yes, this is correct. The light intensity is directly related to the number of photons.

[Arianna Perea 3H]

How come the photons dont have enough energy with low frequency lights?