Mirror and Image
Light will reflect at a mirror surface so that the angles of incidence and reflection are equal.
This java applet shows how an image is formed due to light reflection.
Enjoy it and play with it while learning physics!
Usage:-
Moving the mouse within the area of the mask will show different light paths.
You can click and drag the mask to different positions.
Clicking the area outside the mask will show what happens to light emitted at that location.
You can draw an object with the mouse by clicking and dragging. The image of your drawing will be shown. (example)
Mirror Game
This is a game for you to play and learn physics of light reflection from mirror.
Usage:-
You are suppose to move the gray at the top-right corner to the blue circle position.
Drag the mouse to move the gray circle. There is a mirror image of the path you should follow.
When you click the mouse near the gray circle, your score starts to count down one by one.
If your mouse move outside the boundary, more score will be subtracted.
Can you get score higher than 90 points? Try it! It is fun!
Multiple Reflection from two plane mirrors
Rays of lights are reflected from the mirror, each ray satisfying the law of reflection.
It is fun to play with two plane mirrors, multiple images are formed.
Would you like to try it with this java applet?
Usage:-
There are two plane mirrors with an initial angle of 120 degree.
Click the green circle and drag the mouse to change the angle.The red circle (with yellow background) and the blue line on the left of the mirror , represent the object to be play with.
Click inside the red circle or near the end of blue segment and drag the mouse to change size/location/orientation of the object.Rays of light will emit from the red circle if you click mouse button twice.
Right click the mouse button to show the relations between images.
Find out the light paths and their relations to the images.
Play with it and enter the physics of optics.
Reflection/Refraction
This java applet shows the physics behind a beam of light impinging at some angle on the smooth/rough surface. (reflection/ total internal reflection/diffuse reflection and refraction)
Usage:-You will find a flashlight under the water surface. (Picture)
-
Click the blue region and drag the mouse
button to move the flashlight.
Click the green region and drag the mouse button to change the direction of the flashlight.
Some of the light were reflected back to the water,
-
and some of the light beam change their direction (refracted) into the
air.
Click the blue region twice, and the flashlight will turn into a laser pointer. (picture)
You can move or change direction of the the laser point with similar way as metioned above.
In laser pointer mode: click the water/air interface will change the property of the interface.
Toggle between flat surface/rough surface.
In rough surface mode: watch the diffuse reflection.
In flat surface mode: a circle will be shown while drag the mouse button.
-
the length of yellow bar = the length of orange bar => law of reflection
The length of red bar/the length of yellow bar = constant (index of refraction)
-
=> law of refraction (Snell's law).
Enjoy/Play the java applet and learn the physics behind it!
Prism: Reflection and refraction
This java applet let you play with a light source and a prism, to study the physics of light.
There are reflection and refraction occurs at the interface between two media.
(Total internal reflection might also occurs)
Usage:-
Click the red region to change the light direction.Things to watch:
Click other region of light source can move the light pen to differ location( even inside the prism).
Click one of the corner of the prism to change the shape of prism.
Click inside the prism to change its location.
When tracing of the light will terminated when the ray intensity is less than than 0.4%.
The relative intensity for each ray is shown at the boundary.
Intensity of red and green are used to represent two different polarization.
The yellow light (sum of red light and green light) represent equal intensity of two polarization waves.
At Brewster's angle, only one of the polarized light is refracted, and other one is totally reflected.
The index of refraction for the prism is 1.5
1. Total internal reflection
2. Change in light intensity
3. There might be small bugs, did you find out?
Thin Lens (converging/diverging lens/mirrors)
| blue lines | trace of light path |
| green lines | backward tracing for virtual image |
| small red lines | distances f and 2*f away from the center of lens. |
| 1st textfield | current mouse position (x , y) relative to lens |
| white vertical line | reference line (you can click and drag it left/right) |
| yellow line | light path for paraxial ray assumption(mirror only) |
Parameters can be changed :
- Select Lens for thin lens effect(default)
- select mirror for concave/convex mirror effect
- default: assume paraxial ray (you can turn it off)
- press toggle button +/- to change between converging/diverging lens
- Move the object
- click near tip of the object, and drag it to where you like it and release the mouse button.
- Move the lens/mirror:
- click near center of the lens, and drag it to left or right.
- if click with left mouse button, only lens will move.
- if click with right mouse button, object will move with lens.
- Change the focus length of the lens/mirror
- click near the top/bottom of the lens/mirrir, then drag the mouse . Try it!
- if you adjust the size of window, parameters reset to default values.
- you can change the following parameters inside the "textfield".
| Parameters | distance | defaults |
| P | object | 20. |
| q | image | 20. |
| f | focus | 10. |
| m=-q/p | magnification | 1 |
Thin Lens combinations
This java applets let you understand the entire range of behavior of a single convex lens or image formed by two lens.
How to use it:
You will see single convex lens and a block with four different at each corner.
You will also find images for those corner.
It is like viewing the image of a 3 dimensional object.
The image is distorted and its length is reduced more than its height.
The magnification transverse to the axis is greater than the longitudinal magnification along the axial direction.
Click within the area of the block will show light path for different points.
The location for the object p and object q are shown near the top,
the focus length are labeled at the bottom.
You can click within the small circle at the focus point
and drag the mouse to change the focus point.
Click at the top left corner of the block and drag the mouse to move it.
Click the bottom right corner of the block and drag it to change its size.
The mouse position is displayed as ( x, y ) value.
Click the right mouse button to have another lens,
Click it again to remove it.
x2 is the location of the mouse tip relative to the second lens.
d is the distance between two lens.
You will find image formed by two lens.Click within lens area and drag the mouse to move the lens.
Click the circle between lens to change the focus length. You can simulate image formed by lens combination experiments with this java applets.
All the related parameters are shown, record it and perform a virtual experiment.
Emulate refracting telescope:
Enlarge the image of a distant object.
The object is at a finite far distance from the device, so that the intermediate image is located beyond the image focus of the objective.
The inverted intermediate image served as the object for the eyepiece, which function as a magnifier.
Magnifying power = f1 / f2Emulate compound microscope:
The lens system closest to the object is the objective.
It forms a real, inverted, magnified image of the object that is then viewed by the eyepiece.
The latter is essentially a magnifying glass that looks at and enlarge the image created by the objective.
The total angular magnification od the system
= d * 25.4(cm)/ (f1 *f2)
