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Computer-based optics experiments with curved mirrors using Java applet - Succeed in Physical Science. Also refer to physics, focal point, telescope, microscope, magnifying glass, lens laws, Ron Kurtus, School for Champions. Copyright © Restrictions

Simulated Optics Experiments:

Curved Mirror

by Ron Kurtus (revised 26 October 1999)

Have you ever seen the effects of a concave mirror—like the type used to magnify things?

The following Java applet allows you to simulate optical experiments on your computer. You can study how a lens will focus a light source or make an image, study how a curved mirror works, and see the effect of apertures.

(Note that your browser must be capable of using Java 1.1 for this simulation to work. It is a relatively large applet (115K), so it may take up to a minute until it is completely downloaded. You will see the illustration below in black with a line through the middle, when it is ready to use.)

In this computer-based experiment, you will:

  1. Place the lens on the optical axis.
  2. See how parallel light focuses at a point.
  3. See what happens when a source is put at the focal point of the mirror.

Instructions

Follow these instructions to guide you through the experiments.

1. Place the mirror on the optical bench

  1. Click your mouse on the Mirror button. The text becomes colored, showing it is active.
  2. Click about 1/4 of the way from the right side, near the yellow line. A curved mirror appears. (Jump to optical bench to start.)

NOTE: If you make a mistake, you can click on the Clear Active button to erase the active element or the Clear All button to erase everything.

2. Show the effect of a parallel beam of light

A parallel beam of light will reflect off the concave curved mirror and focus to a point. This principle is used in solar heat to focus the almost-parallel light from the Sun to a point that will become very hot.

  1. Click the Beam button.
  2. Click about 1/4 of the way from the left side, near the yellow line.
    • A beam of light appears. The beam shines on the mirror, reflects, and focuses through a point on the yellow axis.
  3. Click on the focal point and drag it left and right.
    • This shows what happens when the curvature of the mirror changes.
  4. Click on the source of the beam and click the Clear Active button to erase the beam, or simply click the Clear All button to start all over.

3. Show the effect of a source of light at the focal point

A source of light at the focal point of a concave mirror will reflect out parallel to the mirror. This is seen in flashlights and automobile headlights, where the light bulb is at the focal point of the reflector.

  1. Start with a curved mirror near the right end of the optical axis. If the mirror focal points are not visible, click on the mirror to show them.
  2. Click the Source button.
  3. Click on the yellow axis near the focal point. Light rays should come from the source, reflect off the mirror, and go out parallel from the mirror along the axis.
  4. If the light is not parallel, drag the source until it is exactly on the focal point. If the light is not aligned with the axis, drag the source until it is exactly on the yellow optical axis.
  5. Click on the source of the beam and click the Clear Active button to erase the beam, or simply click the Clear All button to start all over.

The optical bench

The simulated optical bench is seen below.

Credit for applet

Special thanks go to Mike Lee, Wolfgang Christian and the WebPhysics staff at Davidson College in Davidson, South Carolina for developing this Java applet and making it available.

In conclusion

Concave mirrors can be used to focus light to a point as in a solar heater and send out parallel beam of light as in a flashlight. They can also be used to create images, but that is better illustrated with lenses.

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Experiments

Simulated Optics Experiments - Curved Mirror

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Optical Devices
Simulated Optics Experiments - Lenses


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