Question

Study of low of reflection of sound and verify it by low of reflection

Answer 1

Answer:

1. The incident wave, the reflected wave, and the normal at the point of incidence lie on the same plane.
2. The angle of incidence is equal to the angle of reflection.

Explanation:

Step 1: In this experiment, very low-amplitude sound waves are heard so peaceful atmosphere is important. Fan is also off to hear the sound clearly.

Step 2: Using a chalk piece or a pencil, draw a line ON on the table (as shown in Fig. 44.2) normal to the wall surface.

Step 3: Now draw a line OC making an ∠i 1 (say 30°) with the line ON

.Step 4: Put one of the two plastic pipes (say PQ) along this line OC such that the end P of the plastic pipe is very close to point O on the wall. Now the axis of pipe PQ lies over the line OC (Fig. 44.2).

Step 5: Now put the second plastic pipe RS on the table, keeping its end R towards the wall on the other side of the normal ON. Mark the position of end R on the table.

Step 6: Keep the table-clock close to the open end Q of pipe PQ.

Step 7: Bring your ear close to the end S of pipe RS. Try to hear the sound of the table-clock through this pipe. Do you hear any sound? Keeping the position of the end R, adjust the position of pipe RS on the table to hear the sound of the table-clock. Mark the position of end S of the pipe RS where you hear the maximum sound.

Step 8: Draw a line OD joining the point O on the wall, the point representing the position of end R, and the point representing the position of end S

.Step 9: Measure ∠NOD. This is the angle of reflection (say ∠r 1 ) for angle of incidence ∠i 1 . Record observations.

Step 10: Keeping the position of the end R fixed, lift the end S of pipe RS vertically to a small height. Are you able to hear the sound of the table-clock through the pipe RS? If yes, lift end S pipe vertically to some more height. Do you still hear any sound? You will observe that on raising the height of end S, the sound of the table-clock either weakens or completely diminishes.

Step 11: Repeat step 2 onwards for three different values of angle of incidence ∠i and find the corresponding values of angle of reflection ∠r.

Step 12: You might have drawn several lines on the table. As courtesy to the students coming to perform this experiment next, it is advised to remove all the lines drawn on the table.