High Frequency = Energy?

[Ian_Lee_1E]

Hey guys,

Through the use of Photoelectric effect, Professor talks about how lights, or photons exactly, with high frequencies have higher energy. Why is it so?

And in the real world, what does increasing the intensity of the light mean? How do you increase the amplitude of the wave?

[Cecilia Cisneros 1F]

To answer your first question, I believe Dr. Lavelle is referring to the equation:
E = h*v
E = energy of photon
h= Planck's constant
v = frequency

Based on that equation, you can see that energy and frequency are proportional to each other. As the frequency of a photon increases, so should the energy and vice versa.

[anikamenon2H]

Like Cecilia said, the relationship between frequency and energy can be found in the equation E = hv. Since E (energy) and v (frequency) are on opposite sides of the equal sign, they are directly proportional; if they were on the same side (such as wavelength and frequency are in c = λ * v) they would be inversely proportional. Since energy and frequency are directly proportional, this means that when one goes up the other goes up --> higher energy = higher frequency.

In the real world or classical mechanics, increasing the intensity means that the light is brighter. The amplitude of a wave can be increased by increasing the energy because amplitude is another form of intensity.

Hope this helps!

[Aaron Akhavan-Dis1B]

Hey guys,

Through the use of Photoelectric effect, Professor talks about how lights, or photons exactly, with high frequencies have higher energy. Why is it so?

And in the real world, what does increasing the intensity of the light mean? How do you increase the amplitude of the wave?

Hi Ian,
I believe increasing the intensity of the light means that the number of photons in the beam is increased because they are proportional. This does not mean that energy is increased, however. Using the formulas, E=hv and , you can see how wavelength and frequency are proportional to the energy. I thought the amplitude of the wave is the number of photons or the intensity of the light. That could be an explanation as to why the intensity is independent of the wavelength, frequency, and energy, and how intensity didn't matter in the Photoelectric Effect. My answer to your amplitude question does disagree with Anika's answer, so maybe another person can set it straight :) .

[Jiapeng Han 1C]

According to the equation E=h*f, higher frequency means each photon has higher energy. Intensity is essentially number of photons, so if you increase the intensity of the light, the light beam will get brighter. To increase the amplitude, or intensity of a light wave, in reality you just need to increase the power of the light source to make the light brighter.