Equipment: The triangulation board (mounted on a frame), a laser pointer (mounted on an arm), a paper bullseye (taped to the wall), masking tape, a stepping stool, a meter sick and a 30 meter tape measure.

What it does: The distance across the lecture hall is measured using triangulation.

Concepts Demonstrated: Triangulation.

Classroom assembly:

1. Move the laser pointer arm to the top of the triangulation board and adjust the arm so it is horizontal.
2. Record the height of the laser pointer arm at the pivot point using the meter stick.
3. Turn on the laser pointer and tape the paper bullseye to the wall so that the laser beam is centered in the bullseye.
4. Lower the laser pointer arm.
5. Record the height of the laser pointer arm at the pivot point using the meter stick.
6. Tilt the laser pointer arm up until the laser beam is centered in the bullseye.
7. Record the height of the tip of the laser pointer arm (ie-the end furthest from the pivot point) using the meter stick.
8. Calculate the distance from the laser pointer to the bullseye using the worksheet below (or click here for a print friendly version).
9. Measure the distance from the laser pointer to the bullseye using the 30 meter tape measure to confirm your results.

• The distance between the horizontal black lines on the triangulation board is 0.7m.
• The distance between the laser pointer arm's pivot point and the scale at the tip is 0.8m.

Cautions: Do not shine the laser pointer at the audience. Do not look directly into the laser beam.

Setup Time: Medium.

Difficulty: Medium.

Visibility: Medium. The apparatus is relatively large, but the details, such as the meter stick, cannot be seen from far away.

Related demonstrations:

References: PIRA 1A.XX

Triangulation Worksheet

Original Construction: Made in house.