Optics yo...

[MCAT guy]

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So I was trying to solve this problem,

it had light going into different indexes of refraction, then asked which frequencies were the greatest...

say n1 > n2 > n3

anyway, it is a trick question as the frequencies remain constant. Which is originally what I was thinking BUT

when I started to use equations, my equations led me down the wrong path:

if V = lamda x f and we know that the speed of the wave is decreasing in water, then doesn't that mean the frequency WOULD change? I reason this because I don't see the actually wavelength changing, as the wavelength tells me what color the light is. So if I shoot red light into water, the light stays red so the wavelength must be similar to 700 nm BUT the velocity is dropping, hence the index of refraciton... wouldn't the frequency need to drop with the velocity?

THE FREQUENCY OF A LIGHT RAY IS DETERMINED FROM THE SOURCE OF LIGHT AND IS NOT USUALLY CHANGED BY THE MATERIAL IT PASSES THROUGH.

I can read this sentence, but I am trying to think through it and my thinking must be off.

 

[PiBond]

So I was trying to solve this problem,

it had light going into different indexes of refraction, then asked which frequencies were the greatest...

say n1 > n2 > n3

anyway, it is a trick question as the frequencies remain constant. Which is originally what I was thinking BUT

when I started to use equations, my equations led me down the wrong path:

if V = lamda x f and we know that the speed of the wave is decreasing in water, then doesn't that mean the frequency WOULD change? I reason this because I don't see the actually wavelength changing, as the wavelength tells me what color the light is. So if I shoot red light into water, the light stays red so the wavelength must be similar to 700 nm BUT the velocity is dropping, hence the index of refraciton... wouldn't the frequency need to drop with the velocity?



I can read this sentence, but I am trying to think through it and my thinking must be off.

if there's a light source shining under water and you're out of the water then you'll observe the same color (i believe) because frequency remains constant. if you're under water then the situation becomes a little complex. if the light is monochromatic then you'll observe the same light regardless. if the light is polychromatic light it will change color (i believe)

if you accept that the source of a wave determines its frequency then this equation is easier to apply. so to change the frequency of a wave we must modify the source. therefore, when a light wave enters a new medium the wavelength has to change because light travels slower due to the higher index of refraction.

sorry, words are a little jumbled. hopefully that helped

 

[MCAT guy]

if there's a light source shining under water and you're out of the water then you'll observe the same color (i believe) because frequency remains constant. if you're under water then the situation becomes a little complex. if the light is monochromatic then you'll observe the same light regardless. if the light is polychromatic light it will change color (i believe)

if you accept that the source of a wave determines its frequency then this equation is easier to apply. so to change the frequency of a wave we must modify the source. therefore, when a light wave enters a new medium the wavelength has to change because light travels slower due to the higher index of refraction.

sorry, words are a little jumbled. hopefully that helped

yeah it helped, thx. I guess my flaw was thinking that the color doesn't change which means the wavelength is constant. This appears to be a flawed logic.