help needed for a disillusioned student

[Del]

Good Afternoon, i am currently studing to become a optical technician by mail and i was wondering if yous could help me answer a question.

A lens has a focal length in one meridian of +25cm and at right angles to this meridian a focal length of +50 cm.

What is the power of this lens along its principle merdian's?

A sphero-cylindrical lens +2.50 D.S/-2.00 D.C x V is made up in glass of refractive index 1.52. What are the radii of curvature of the spherical and cylindrical surfaces?

[Dave Nelson]

What is the focal length of 1 diopter? What is the formula to determine the radius?

[chip anderson]

Four diopters and two diopters. 100cm=1diopter. every addittional diopter is equal to the percentage of 100cm at which it converges (or reciprocal divergence. 2dio\=1/2 meter(50cm). 4 diopters=1/4 meter (25cm).

[Dave Nelson]

Thanks Chip, but I was going to try to walk him through it so he/she comes up with the answer themselves.:bbg:

[chip anderson]

Sorry Dave.

[LKahn]

Del

It the course was easy, it would not be valuable or respected.

[EyeFitWell]

Del,
Just remember the definition of a dioptor!

D=1/F(m) Power (dioptors) equals 1 divided by focal length in meters.
or,
F(m)=1/D

It's as simple as that!

[chip anderson]

Dell: Your profs will also be more impressed if you can spell Diopter, it is not Dioptor.

[Trevor D]

Or in this part of the world, it is spelt "dioptre"

[EyeFitWell]

Down here in the south, it's spelled "diaaapteeer"

[Del]

Thanks everyone, i took a couple of days off work and sat myself down and done a good bit of work and i am feeling much better for it. Dioptre is how we spell it here by the way :D

Question was easy to answer after i studied just looks like i need to find more time, ahh well who needs a social life for a couple of years :)