Lens problem

[salemstein]

Hey I was wondering what would the following things do to the focal length of a convex lens: 1) increasing the n of the material used 2) increasing the temperature of the lens 3) increasing the temperature of the surrounding media.

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[theonlytycrane]

for lenses, the focal length is given by the lens-makers eqn:

increasing n -> decreases f.

Not exactly sure about 2) and 3). My guess in the dark based on the equation above is no change.

 

[aldol16]

I would think the temperature thing would depend on whether the temperature change is high enough to cause any significant thermal expansion.