Does shooting a billiard ball against the side bumper of a pool table has same effect as a light ray? Find out in this experiment.
Things Required:
Torch
Small mirror
A ruler
Tape
Directions:
Use tape to place a set of marks along one wall of a hallway or narrow room. Place the first mark 1 foot above the floor. Place the second mark 1 foot above the first (2 feet high). Add two more marks, one at 3 feet high and the final one at 4 feet high. Make sure when you position the marks, they are placed directly atop each other.
Place a mirror in the centre of the hallway floor. The mirror should be placed in line with the set of wall marks.
Dim the lights in the hallway. Position your torch at the 1-foot mark. The back end of the torch should remain in contact with the wall. Aim the beam at the mirror. Observe where the reflected spot appears. Mark this spot with a piece of tape.
Position the torch at the other marks along this wall. Observe and mark where the reflected spot appears. How does the angle at which the torch beam strikes the mirror affect its reflection?
Suppose the beam came from directly above the mirror. Where would the reflected spot appear?
This Is What Happens:
The angle at which the beam strikes the mirror determines the angle of reflection. If the striking beam (also called the incident beam) hits this surface at a shallow angle, the reflected beam will travel outward along a shallow angle. Likewise, if the incident beam strikes the mirror at a steep angle, the reflected angle will also be steep.
In your hallway experiment, the spot always appeared on the opposite wall at the same height from which the beam began. Since the angle of the incident ray equalled the angle of the reflected ray, this spot had to appear at the same height.
