## Light Intensity

Eliana Carney 3E
Posts: 91
Joined: Wed Sep 30, 2020 9:31 pm

### Light Intensity

Just to clarify, when talking about increasing the light intensity during the photoelectric experiment, the scientists were just increasing the brightness of the light? They weren't changing the frequency/wavelength of the light?

Namratha Gujje
Posts: 95
Joined: Wed Sep 30, 2020 9:33 pm

### Re: Light Intensity

I believe so! The light is only getting brighter, it is not changing its frequency/wavelength.

Jasmine Ho 3I
Posts: 89
Joined: Wed Sep 30, 2020 9:41 pm

### Re: Light Intensity

Yes, the intensity of light is related to the number of photons! More photons = brighter light

Charmaine Ng 2D
Posts: 98
Joined: Wed Sep 30, 2020 9:37 pm

### Re: Light Intensity

Yep! They were just increasing the brightness of the light, only increasing the number of photons and not changing the frequency/wavelength, which is how they figured out that it wasn't working! That's when they realized that changing frequency is actually what allows them to cross the threshold energy :))

Rajshree 1F
Posts: 101
Joined: Wed Sep 30, 2020 9:32 pm

### Re: Light Intensity

Yes! The scientists hypothesized that making the light brighter would give the electrons more energy however increasing the number of photons (aka brightness) had no such effect but increasing frequency did.

Jarrett Sung 3B
Posts: 28
Joined: Wed Sep 30, 2020 9:41 pm

### Re: Light Intensity

Yup! When they increase the intensity of the light they are increasing the number of photons, which doesn't end up changing the energy, so in the photoelectric experiment the intensity change didn't increase the electrons released. This was how they realized the frequency changes the energy of the photons.

605291562
Posts: 91
Joined: Wed Sep 30, 2020 10:07 pm

### Re: Light Intensity

Yes! Like everyone else has said they adjusted the brightness. I believe if they would have increased the wavelength there would have been a change.

Helena Hu 3E
Posts: 53
Joined: Wed Sep 30, 2020 9:35 pm

### Re: Light Intensity

I would think that a greater amplitude of a light wave would mean higher intensity, as well. Hope this helps!

josephspindler2H
Posts: 92
Joined: Wed Sep 30, 2020 9:54 pm
Been upvoted: 1 time

### Re: Light Intensity

Yes, you are correct! If they had changed the wavelength or frequency, they would have changed the type of light being shown. As many have already stated, increasing the intensity led to an increase in total photons rather than individual photon energy. This is a problem on the quantum level where an individual photon must have enough energy rather than the whole system, thus frequency must be changed.

Megan Lu 3D
Posts: 90
Joined: Wed Sep 30, 2020 9:49 pm

### Re: Light Intensity

Hi! Yes, I believe that it was only the brightness (intensity) of the light that was increasing, not the actual frequency/wavelength.

Linette Choi 3L
Posts: 93
Joined: Wed Sep 30, 2020 9:51 pm

### Re: Light Intensity

Yup! Increasing the light intensity would just mean the light is getting brighter and the number of photons in increasing but it would not change the frequency or energy of the individual photon where it would have enough energy to eject an electron.

Gicelle Rubin 1E
Posts: 81
Joined: Fri Oct 02, 2020 12:16 am

### Re: Light Intensity

Hi there! You are correct, the wavelength/frequency did not change. It is the photons that affect the brightness of light, so it increased.

Irene Nguyen 2J
Posts: 50
Joined: Wed Sep 30, 2020 9:44 pm

### Re: Light Intensity

Yes, frequency and wavelength remain unchanged! Brighter light means there's an increase of photons.

Serena Song 1A
Posts: 90
Joined: Wed Sep 30, 2020 9:53 pm
Been upvoted: 1 time

### Re: Light Intensity

Yup! The number of photons increases when the brightness increases, but the wavelength/frequency of each photon remains the same. If the wavelength/frequency changed, then that could've changed what type of EM wave it was instead (ex. from visible light to UV light if the frequency increased/wavelength decreased).

Susan Chamling 1F
Posts: 91
Joined: Wed Sep 30, 2020 9:42 pm

### Re: Light Intensity

You're correct, the brighter light was caused by an increase in photons. For the experiment they realized that increasing the intensity of the light did not change the energy of the photons, because it is a change in wavelength/frequency that causes that change.

Gustavo_Chavez_1K
Posts: 92
Joined: Wed Sep 30, 2020 9:46 pm

### Re: Light Intensity

Exactly! So the experiment was basically just them changing the intensity of the light, so making it brighter. This is why they noticed that the electrons were not being ejected. However, once they changed the type of light, so the frequency, that is when the electron were ejected.

Danielle DIS2L
Posts: 92
Joined: Wed Sep 30, 2020 9:38 pm

### Re: Light Intensity

Increasing the light intensity would just increase the number of photons but not increase the frequency.

Nick Saeedi 1I
Posts: 107
Joined: Wed Sep 30, 2020 9:39 pm

### Re: Light Intensity

Yes. They were only increasing the amount of photons which is the intensity not the frequency of light.

Ayesha Aslam-Mir 3C
Posts: 115
Joined: Wed Sep 30, 2020 9:43 pm

### Re: Light Intensity

Only slightly related I suppose, but if the intensity of light is increased, I imagine the wave model would have higher peaks, correct? I thought the height of the peaks and the distance between them (wavelenght) correlated? So then light doesn't act in the wave form because the greater intensity indicates they do not correlate?

Sejal Parsi 3K
Posts: 76
Joined: Wed Sep 30, 2020 10:03 pm

### Re: Light Intensity

Hey! That’s correct, increasing the intensity of the light meant increasing the brightness which is more photons. Had they increased the frequency/changed the wavelength, the experiment would have worked.

905290504
Posts: 124
Joined: Wed Sep 30, 2020 9:44 pm
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### Re: Light Intensity

increasing intensity of light means increasing the number of photons which does make the light brighter. the important point here is that the energy of the indivudal photons doesn't change just the number of them

Annika Tamaki 1E
Posts: 94
Joined: Wed Sep 30, 2020 10:03 pm
Been upvoted: 1 time

### Re: Light Intensity

The intensity of the light refers to the number of photons, and results in no changes to the wavelength or frequency.

Gabriel Nitro 1E
Posts: 95
Joined: Wed Sep 30, 2020 9:32 pm
Been upvoted: 1 time

### Re: Light Intensity

Hi,

Yes! As the intensity of the light increases, we associate that property as increasing in brightness! However, don't forget increasing intensity increases the number of photons!

For example, let's say we have two intensities $I_1$ and $I_2$, where $I_1$ > $I_2$. Thus, $I_1$ would have more photons than that of $I_2$.

Hope this helps! :)

SamanthaTolentino 3D
Posts: 132
Joined: Wed Sep 30, 2020 10:03 pm

### Re: Light Intensity

Increasing the intensity of the light meant increasing the amount of photons being aimed at the metal. Professor Lavelle gave an example with cross country runners and how increasing the intensity of runners meant increasing the number of runners.