# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## JDK1.0.2 simulations (1996-2001) => Optics => Topic started by: Fu-Kwun Hwang on January 29, 2004, 10:51:12 pm

Title: Thick Lens
Post by: Fu-Kwun Hwang on January 29, 2004, 10:51:12 pm

When a beam of light meet the boundary between two different media,
some light is reflected back to the same media
(law of reflection)

some light is refracted to a different media
( law of refraction).

The same laws applied when light wave impinging the surface of a lens.
This java applet let you play with a thick lens.

How to play:
You can enter the index of refraction of the lens into the Text Field.

The gray ellipse area represents the thick lens.
You can click the left mouse button within one of four cyan circle around the lens
and drag the mouse button to change the shape of the lens.

You can click the circle at the center of the ellipse and drag the mouse left/right to move the lens horizontally.
Light beam entering from the left of the screen.

You can click at the beam and drag it up/down. Hit Reset button for default conditions.

Approximate indices of refraction of various substance
 Air 1.00029 ice 1.31 water 1.333 Ethyl alcohol 1.36 Fused quartz SiO2 1.4584 glass 1.5 - 1.6 diamond 2.417 Futile TiO2 2.907 Gallium phosphide 3.50

Title: Re: Thick Lens
Post by: PELADO on May 17, 2008, 11:03:16 pm
OK     ;D
TKS FOR ALL YOU ARE A GENIUS

Title: Re: Thick Lens
Post by: Wieslaw on August 08, 2009, 01:38:31 am
It is really nice, however I would like to suggest making another similar applet, a little more complicated. It could show the rays in a human eye. There just should be some procedures used here repeated more times.

Title: Re: Thick Lens
Post by: leeyiren on December 31, 2009, 04:31:25 am
prof, am i right to say that this simulation is to show us that the thicker the lens, the shorter the focal length?

Title: Re: Thick Lens
Post by: leeyiren on December 31, 2009, 04:45:00 am
can anyone briefly tell me what is the equation in the simulation?

Title: Re: Thick Lens
Post by: Fu-Kwun Hwang on December 31, 2009, 12:45:50 pm
Refraction obey Snell's Law $n_1\sin\theta_1=n_2\sin\theta_2$

Title: Re: Thick Lens
Post by: leeyiren on December 31, 2009, 07:39:10 pm
Refraction obey Snell's Law $n_1\sin\theta_1=n_2\sin\theta_2$

what i mean is the equation "x^2/n+y^2/n=1"

i dun see the snell's law in it?

Title: Re: Thick Lens
Post by: Fu-Kwun Hwang on December 31, 2009, 11:09:08 pm
$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$ is the equation for the shape of the lens (equestion of Ellipse).
Snell's law is used to calculate the ray refraction when light enter into lens and get out of the lens.
You should be able to find it in the code.

Quote
am i right to say that this simulation is to show us that the thicker the lens, the shorter the focal length?

Yes. The focal length getting shorter when lens is getting thicker.
When the lens is too thick or when the ray is too far from the axis, there might be a single focual point any more.
Please check out Lens (thick lens) and Mirror (http://Lens (thick lens) and Mirror).