Light & Optics Question

[HopefulOncoDoc]

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When parallel rays of white light pass through a glass lens:

A. the rays all meet at the same focal point.
B. the index of refraction of the glass is the same for all the colors.
C. the focal length for violet light is smaller than the focal length for red light.
D. whether the rays all have the same focal point depends on whether the lens is converging or diverging.

The answer is C.

So v = (Lambda)f and n = c/v. Because Violet light has a smaller wavelength, its v will be smaller and thus its n (index of refraction) should be greater than that of the red light. Shouldn't it be then that the focal length for violet is greater than that of red light since red light would refract more? Thanks.

 

[IntelInside]

When parallel rays of white light pass through a glass lens:

A. the rays all meet at the same focal point.
B. the index of refraction of the glass is the same for all the colors.
C. the focal length for violet light is smaller than the focal length for red light.
D. whether the rays all have the same focal point depends on whether the lens is converging or diverging.

The answer is C.

So v = (Lambda)f and n = c/v. Because Violet light has a smaller wavelength, its v will be smaller and thus its n (index of refraction) should be greater than that of the red light. Shouldn't it be then that the focal length for violet is greater than that of red light since red light would refract more? Thanks.

Longer wavelengths (lower frequencies), such as red light, move faster through a medium than shorter wavelengths (higher frequencies), such as violet light, and therefore bend (refract) less dramatically at the media interface!!!

 

[FlipDoc2Be]

Longer wavelengths (lower frequencies), such as red light, move faster through a medium than shorter wavelengths (higher frequencies), such as violet light, and therefore bend (refract) less dramatically at the media interface!!!

I thought that the frequency of waves is not typically altered as it travels through some medium. So since v = (lambda)f , shouldn't red light travel faster through a medium since its wavelength is greater?

 

[IntelInside]

you just restated what I said.....I dont understand where you are being confused now

 

[FlipDoc2Be]

Nvm. Figured it out. Thanks!