Physics Demo Number: 021

Approximate

Run Time: 5 min

Plane Mirror Incident And Reflected Rays

Demo Description

Show a beam of laser light reflecting from a plane mirror with the aid of chalk dust.

Scientific Principles

• For a light ray impinging at a non-normal angle to a plane mirror, one finds that the incident and the reflected rays form equal angles with the normal to the mirror at the point of impingement and are contained in a plane along with the normal to the surface.

Equipment

• The large He-Ne Laser

• A set up pole with an adjustable clamp

• A Plane Mirror

• Chalk Dust

Equipment Location

• The 5 mW laser lives on [C-2-4].

• The set up pole and clamps are in the common hardware shelves in the [G-1-x] and the [G-2-x] columns.

• The mirror resides in Kit(132) on [C-1--3].

• Chalk dust is usually quite easily found in the classroom.

Instructions

The set up is shown in the photo.

Tapping two chalk-board erasers together above the impact point of the laser beam on the mirror surface will display the incident and reflected beams quite nicely.

Writeup created by David A. Burba

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