Reflection and Rarefaction (Waves)

Question 1

Reflection:

Answer 1

The wave bounces off the new medium

Question 2

Transmission:

Answer 2

The wave starts moving through the new medium.

Question 3

Absorption:

Answer 3

The wave’s energy is absorbed by the new medium.

Question 4

Echo:

Answer 4

When a reflected sound wave reaches your ears more than 0.1 seconds after you hear the original, you hear this reflected sound as a echo.

Question 5

Reverberation:

Answer 5

When the time interval is shorter then 0.1 seconds you hear the reflected sound and the original sound as a single sound. The overlapping of sound waves is known as reverberation.

Excessive reverberation can make speech harder to comprehend.

Question 6

Speed of sound and speed of light.

Answer 6

Sound travels faster when there is a smaller distance between the particles in the medium. As a result it travels fastest in solids then in gases.

For light, as density increases the speed of light decreases.

Speed of sound is also affected by temperature, as temperature increases the average kinetic energy of the particles also increase hence they are moving faster and transferring energy faster.

Question 7

Refraction:

Answer 7

When a wave moves from one medium to another it changes its velocity.

-The frequency remains constant.
-wavelength changes
-if the wave enters the new medium at a angle, it refracts (changes direction)

Wavefronts refract because the part of the wavefront that reaches the boundary first slows down(or speeds up), while the remainder of the wavefront still in the original medium continues at the same velocity.

Question 8

Refraction of Sound:

Answer 8

When a wave entering a denser or hotter medium:
- velocity and wavelength increases
- The wave bends away from normal

When entering a less dense or cooler medium:
- Velocity and wavelength decrease
-The wave bends towards normal

Question 9

Temperature gradient:

Answer 9

During the day the air close to the ground is warmed by the hot ground. The air higher up is cooler, creating a temperature gradient.
Sound travels faster in warmer air, so the edge of the wavefront close to the ground travels faster than the edge of the wavefront in the cool air. This causes a gentle refraction (bending) of the wavefronts away from the ground.

Question 10

Critical angle

Answer 10

When sound enters a medium where its speed is greater, the wave bends away from the normal.

Eventually the angle of refraction reaches 90°, and the wave travels along the interface between the two media. The angle of incidence that causes this to occur is known as the critical angle.

If the angle of incidence is greater than the critical angle (0; > 0), refraction no longer occurs the wave is entirely reflected and does not enter the other medium. This is known as total internal reflection.