Is it snells law i use

[NicolaKirk]

Please can someone help i'm currently in my first year ABDO, i'm a bit stuck on a question ok here goes

What is the difference in the apparent thickness of a biconvex lens, made in glass of refractive index 1.5, having radii of curvature of 8cm and 20cm and central thickness 2cm, the lens first being examined from one side and then from the other?

I know thats what i thought:hammer:
Please can you help

[NicolaKirk]

Can no one help me

[Dave Nelson]

Sorry, but I can't make sense of your question. Can you post it word for word?

[chip anderson]

It would probably look thicker when viewed from the side with the shortest radius. Is that what you want to know? Or do you want to know which side would have more appearent magnification at X distance.

Chip

[NicolaKirk]

Hi Dave and Cip thanks for even looking at the question :cheers:

I have written the question word for word that is in my assignment book, i think they want me to work out the center thickness, however the rest of the question i dont understand i think i may just have to give up on this one!

Thanks guys for your help anyhow :cheers:

[Darryl Meister]

Most likely, they want you to calculate the difference in vergence from the two lens surfaces, as seen through either side of the lens. When observing the depth of an object within a medium, which in this case represents the depth of the opposite surface of the lens as viewed through the lens material, the apparent depth or reduced thickness can be calculated using the conjugate foci formula:



where d represents the reduced thickness, n represents the refractive index of the lens material, r represents the radius of curvature of the surface toward the viewer in meters, and t is the real center thickness of the lens in meters. This assumes that the surrounding medium (air) has a refractive index of 1.

If you solve this equation for d using both lens surfaces, you can calculate the difference in apparent depth or reduced thickness when viewing the lens through either surface.

[bob_f_aboc]

Most likely, they want you to calculate the difference in vergence from the two lens surfaces, as seen through either side of the lens. When observing the depth of an object within a medium, which in this case represents the depth of the opposite surface of the lens as viewed through the lens material, the apparent depth or reduced thickness can be calculated using the conjugate foci formula:



where d represents the reduced thickness, n represents the refractive index of the lens material, r represents the radius of curvature of the surface toward the viewer in meters, and t is the real center thickness of the lens in meters. This assumes that the surrounding medium (air) has a refractive index of 1.

If you solve this equation for d using both lens surfaces, you can calculate the difference in apparent depth or reduced thickness when viewing the lens through either surface.

The 8cm radius lens will appear .6mm thinner than the 20cm radius.

If I did the math correctly.

Someone let me know.