Angle of Incidence

[MedPR]

For parallel rays of white light incident on a spherical mirror, the light's color components have focal lengths that:

A. are independent of the component frequency.
B. increase as component frequency increases
C. decrease as component frequency increases
D. increase as the component frequency increases, for concave mirrors only; convex mirrors would yield the inverse relationship between focal length and frequency.

Answer is: A

The explanation is that angle of incidence = angle of reflection and is independent of frequency and refractive index. I understand that. I don't understand how you know that this is talking about reflection and not refraction? I thought it was C, since nlambda=nlambda and as frequency increases, wavelength decreases, so n increases and the refracted rays bend more, thus shortening (decreasing) the focal length.

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[chiddler]

because it's a mirror!

 

[MedPR]

because it's a mirror!

Are you implying that with mirrors the image is always formed on the same side as the object, making refraction irrelevant? If so,

 

[chiddler]

no, but i think you have the term diffraction confused with something else. diffraction only is relevant to how light bends when changing mediums.

since it's a mirror, light is not changing mediums and refraction is irrelevant.

 

[MedPR]

no, but i think you have the term diffraction confused with something else. diffraction only is relevant to how light bends when changing mediums.

since it's a mirror, light is not changing mediums and refraction is irrelevant.

I'm talking about refraction, not diffraction. Diffraction is in regard to shooting light through a small hole, refraction is how light bends through different media, like air into a glass mirror.

 

[chiddler]

I'm talking about refraction, not diffraction. Diffraction is in regard to shooting light through a small hole, refraction is how light bends through different media, like air into a glass mirror.

wowow. i was thinking of the right word but typed it wrong. i think.

correction: yes. refraction is irrelevant to mirrors since light doesn't change mediums at any point. it only reflects.

so the only possibility is reflection. not refraction.

 

[411309]

For parallel rays of white light incident on a spherical mirror, the light's color components have focal lengths that:

A. are independent of the component frequency.
B. increase as component frequency increases
C. decrease as component frequency increases
D. increase as the component frequency increases, for concave mirrors only; convex mirrors would yield the inverse relationship between focal length and frequency.

Answer is: A

The explanation is that angle of incidence = angle of reflection and is independent of frequency and refractive index. I understand that. I don't understand how you know that this is talking about reflection and not refraction? I thought it was C, since nlambda=nlambda and as frequency increases, wavelength decreases, so n increases and the refracted rays bend more, thus shortening (decreasing) the focal length.

you are thinking way too far into this. The focal length if the property of the mirror and it will stay constant. Mirrors operate on the concept of reflection, lenses use refraction so think very carefully when trying to apply snells law and the thin lens equation. If you put a mirror underwater it will have the same focal length; if you put a lens underwater it will change.

I should add im talking about spherical mirrors btw.