# Mirrors

## O.3(1a) - Suspended Ball

A 2 cm diameter orange ball is suspended by a long nylon thread in front of a parabolic concave mirror, of about 20 cm diameter. When the ball is swung toward the mirror, its image appears to come in the direction of the observer, growing in size.

Another ball with differently colored hemispheres can be set in place. As the ball swings towards the mirror, one can clearly see that the image inverts and enlarges.

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## O.3(1b) - Illusion

Two parabolic concave mirrors of same diameter, about 20 cm, are identical except for a 3 cm diameter hole on the center of the top one. They are set facing each other: one sitting on a table and the other on top. On the bottom one, on its center, is placed a small magnetic needle (or anything you like). A very clear three-dimensional image of the magnetic needle is produced on the surface of the top mirror. The needle appears to be exactly were there is a hole, as if you could reach out and touch it. It displays an unusual optical effect. The object on top can be even photographed or, shine a laser beam on it and the beam will be reflected.

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## O.3(2) - Two Mirrors-Multiple Images

Two plane mirrors set perpendicularly to each other form three images on an object placed between the mirrors. When the angle of the two mirrors are decreased extra images appear.

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## O.3(3a) - Candle Burning at Both Ends

A horizontal candle is seen burning at one end (flame up) and at the other (flame down) when viewed at the candle's level. It is an illusion caused by the spherical concave mirror. When an object is at the center of curvature of a spherical concave mirror a real image is formed that is inverted and the same size as the object.

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## O.3(3b) - Spherical Aberration for Mirrors

It can be shown in the Optical Laser System, see O.1(1).

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## O.3(3c) - PASCO Demonstration Mirrors

Extra large mirrors are a great way to teach students about image formation. Watch the amazement on their faces as they observe a real image hanging in space before their eyes produced by the concave mirror. Use the convex mirror to demonstrate why they are used for security purposes in many retail establishments.

The mirrors combine large size and a sturdy stand for ease of use during demonstrations. Each silver-backed, non-aluminized mirror measures 60 cm in diameter with a 45 cm focal length. Unique clamp on stand allows mirror to be adjusted to any angle.

Concave Mirror

Convex Mirror

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