In: Physics
A symmetric double convex lens with a focal length of 28.0 cmcm is to be made from glass with an index of refraction of 1.51. |
Part A What should be the radius of curvature for each surface? Express your answer to two significant figures and include the appropriate units. |
Use the lens maker's formula:
1/f=(n-1) [(1/R1)-(1/R2)]
Given,
focal length.(f=28 cm =0.28 m given).
n is refractive index of material of lens relative to surrounding medium. (n=1.51 given).
R1 is radius of curvature of first surface.
R2 is radius of curvature of second surface
R1=R2=R given.R1 is positive and R2 is
negative in Cartesian sign convention.
Then,
(1/f)=(1.51-1)(2/R). Or
(1/0.28)=(0.51)(2/R)=1.02/R.
Therefore,
R=(1.02)(0.28)m=0.2856 m ~=28.56 cm.
Hence,R=28.56 cm
or R= 0.2856 m (answer)