Waves and Wave Motion

Question 1

Travelling Mechanical Wave

Answer 1

A travelling mechanical wave is a disturbance carrying energy through a medium without any overall motion of that medium

Question 2

Travelling Wave

Answer 2

A travelling wave, either mechanical or electromagnetic, is a disturbance that travels out from the source producing it, transferring energy from the source to other places through which it passes

Question 3

Transverse Wave

Answer 3

A transverse wave is a wave where the direction of vibration is perpendicular to the direction in which the wave travels

Question 4

Longitudinal Wave

Answer 4

A longitudinal wave is a wave where the direction of vibration is parallel to the direction in which the wave travels

Question 5

Unit of Frequency

Answer 5

The unit of frequency is the hertz (Hz), where:
1 hertz = 1 cycle per second
1 Hz = 1 /s

Question 6

Reflection

Answer 6

The bouncing of waves off of an obstacle in their path is called reflection of waves

Question 7

Refraction of Waves

Answer 7

The changing of direction of a wave when it enters a region where its speed changes is called refraction

Question 8

Diffraction

Answer 8

The sideways spreading of waves into the region beyond a gap or around an obstacle is called diffraction

Question 9

Interference

Answer 9

When waves from two sources meet, a new wave is produced. The displacement produced at any point by this wave is the algebraic sum of the displacements that each wave would produce on its own. This is called interference of waves

Question 10

Constructive Interference

Answer 10

When waves from two sources meet and the amplitude of the resulting wave is greater than the amplitude of each of the individual waves, the waves are said to undergo constructive interference

Question 11

Destructive interference

Answer 11

When waves from two sources meet and the amplitude of the resulting wave is less than the amplitude of each of the individual waves, the waves are undergoing destructive interference

Question 12

Coherent Sources

Answer 12

Two sources of periodic waves are said to be coherent if they are in phase or if there is a constant phase difference between waves from each of the sources. If this is so, the sources must also have the same frequency

Question 13

Interference Pattern

Answer 13

When waves from two (or more) coherent sources meet, the resulting wave pattern formed is called an interference pattern

Question 14

Stationary Wave

Answer 14

When two periodic travelling waves of the same frequency and amplitude moving in opposite directions meet, they interfere with each other. The resulting wave formed is called a stationary wave or a standing wave

Question 15

Frequency and Wavelength of a Stationary Wave

Answer 15

The frequency of vibration of every vibrating particle in a stationary wave is the same
The frequency of a stationary wave is the same as the frequency of the travelling wave producing it

Question 16

Doppler Effect

Answer 16

The apparent change in frequency of waves due to the motion of the source or the observer is called the Doppler effect.
If a source emits waves of frequency f, the observed frequency f’ will be:
Greater than f if the source moves towards the observer or the observer moves towards the source
or
Less than f if the source moves away from the observer or the observer moves away from the source