2polnts
what type of device forms images by changing the direction
but not the speed at which light travels?
o a. any convex device
o b. any lens
o c. any concave device
o d. any mirror
submit

D. Any mirror

Explanation:

The main difference between mirrors and lenses is the following:

- Mirrors work based on the principle of reflection: reflection occurs when a light ray hits a surface and it bounces back in the same medium changing direction, withouth crossing the interface between the two mediums. In this case, the speed of the light ray does not change, since it depends only on the refractive index of the medium, n:

where c is the speed of light in vacuum: and since the light ray is reflected into the same medium, n does not change, so the speed does not change.

- Lenses work based on the principle of refraction: refraction occurs when a light ray crosses the interface between two mediums, changing direction. However, in this case the speed of the ray also changes: in fact, the ray is now in a different medium, so according to the equation

the speed of the light ray has also changed.

Therefore, the correct answer is

D. Any mirror

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explanation:

b mirrors submit a iisner? e. for which optical devices does d sometimes have a positive value? o a a and b o b. a and c o c. b and d 0 d. b and cb