Understanding Wave Reflection: Plane and Curved Obstacles

Wave Reflection Study

Purpose

To study the reflection of a plane wave, generated by a wave source, off different obstacles.

Planning

1. Position the right triangle reflector in the form of a right angle.
2. Generate plane waves incident upon the reflector.
3. Affix paper to the table. Use a ruler to draw one or more lines to show the front of the incident wave and the reflected wave front. Ensure the ruler is parallel to the corresponding disturbance.
4. Trace the position of the reflective barrier.
5. Repeat steps for two other positions of the triangle.

Part 2: Reflection in a Curved Obstacle

1. Trace the circular barrier on a new sheet of paper.
2. Mark the position where the reflected waves converge.
3. Turn off the generator. Use your fingertip to produce a circular pulse at the marked position where the waves converge.

Procedure

Draw a perpendicular line to the incident wave front (incident ray) until it reaches the reflective barrier. Then, draw a line from the point of intersection of this ray with the barrier, crossing the reflected wave front perpendicularly (reflected ray).

What does this line represent?

This line represents the normal to the reflector barrier.

Draw the perpendicular at the point of intersection on the barrier.

Measure the angle of incidence (θi) and the angle of reflection (θr). Complete Table 1.

Conclusions

θi tends to be equal to θr, although in theory, they should be equal.

Part 2: Curved Reflection on an Obstacle

What can you say about the shape of the pulse after being reflected by the barrier?

The reflected rays converge at one point, called the focus.

The point where the waves converge is called the focus. The distance to where the reflected wave converges is half the distance of the radius.

In this laboratory experiment, we have demonstrated empirically that the incident and reflected angles are approximately equal, considering various test cases (3). This can be verified in the table.

In the case of the circular barrier, we verified the existence of a point where the reflected rays converge; this point is called the focus.

The relationship between the source and the radius of the circular barrier is approximately 1:3.