You are here:

Advertisement

A convex lens has refraction of 1.5 and 20 cm length of radius of both plane. What is the power of lens?

Assuming that n=1.5 is the index of refraction and that this is a double convex lens with both radii of curvature of R=20cm, the focal length of this lens will be given by the "Lensmaker's Formula":

1/f=(n-1)*(1/R1+1/R2)=(1.5-1)*(1/20+1/20)=0.5*(2/20)=0.5*(1/10)=0.05

Therefore the focal length ofthe lens f will be:

F=1/0.05=20cm

The corresponding "power" Mx of the lens is equal to 100cm divided by the focal length of the lens in centimeters:

For this lens the power will be:

Mx=100cm/20cm=5 diopters

It is worth noting that this is only an approximation since the actual magnifying power of a lens also incorporates the human eye which varies from individual to individual.

- Add to this Answer
- Ask a Question

Rating(1-10) | Knowledgeability = 10 | Clarity of Response = 10 | Politeness = 10 |

Comment | I am very glad to get answer and I always thank him. |

Careers: Teaching

Answers by Expert:

I am teaching or have taught AP physics B and C [calculus based mechanics & electricity and magnetism] as well as Lab Physics for college bound students. I have a BS in Physics from the University of Pittsburgh and a Master of Arts in Teaching from same. I have been teaching physics for 27 years.