A converging lens of a diamond and a lens of crown glass have the same shape?
Which lens will have the greater focal length? Explain your answer.
Index of refraction of diamond = 2.42
Index of refraction of crown glass = 1.52
Both are converging lenses.
OpenRoad
on November 30th, -0001
You don’t need to actually figure out the FLs, since this is a greater than/less than question. The lower index of refraction gives less convergence which results in a longer FL.
KittyInCollinder
on November 30th, -0001
To answer this, you will need to use the lensmaker’s equation, (or the thin lens equation). Using that equation, determine whether the focal length is proportional to, or inversely proportional to the refractive index of the lens. This will give you all the information you need.
CookieMonster
on November 30th, -0001
When the shapes are equal the focal length of a converging lens is inversely propotional to ( refractive indedex minus one).
Therefore, the focal for diamond lens will be less than that for crown glass.
The formual for focal lenght is 1/f = ( mu-1) { 1/R1+1/R2)
If fd is the focal length of diamond and fc is for crown glass fc/ fd = 1.42/ 0.52 =2.73.
The focal length of crown glass lens will be 2.73 times greater than that for diamond lens.