A convex lens of power +6 dioptre is placed in contact with a concave lens of power -4 dioptre. What will be the nature and focal length of this combination.
Answers
Yes, a higher cylindrical power would require a thicker spectacle or contact lens to correct the refractive error. The axis will just specify where on the lens the thickest portion would be.
SO THE FORMULA IN FINAL POWER =P1+P2-DISTANCE BETWEEN THEM ... The two lenses of power +12 and -2 dioptres are placed in contact; find the power ... Two convex lenses with a power 2 diopter are kept in contact with each other.
LET THE POWER OF THE TWO LENSES BE P1 AND P2.
SO THE FORMULA IN FINAL POWER =P1+P2-DISTANCE BETWEEN THEM MULTIPLIED BY P1P2
P=P1+P2-dP1P2(MATHEMATICAL REPRESENTATION)
IN THE FIRST CASE DISTANCE BETWEEN THE LENSE IS O THEREFORE d BECOMES O AND WE GET P =P1+P2
LET THIS BE EQUATION 1..
NOW IN THE SECOND CASE d is 0.25 SO EQUATION 2 BECOMES P=P1+P2-0.25P1P2
SOLVING THE TWO EQUATIONSWE GET P1=8 , 2 AND P2 =2,,8...