wave behaviour - basics

Question 1

Define ‘wave’

Answer 1

A vibration which transfers energy without transferring matter

Question 2

define ‘transverse’

Answer 2

oscillations are perpendicular to the direction of propagation

Question 3

define ‘longitudinal’

Answer 3

oscillation are parallel to the direction of propagation

Made up of compression and rarefactions

Question 4

define ‘wavelength’

Answer 4

distance from one point on a wave to the same point on the next wave, measured in metres
(eg. crest to crest or trough to trough)

Question 5

define ‘period’

Answer 5

Time taken for a whole wave to pass a specific point

Question 6

What is the symbol for period

Answer 6

T

Question 7

What is the equation for period?

Answer 7

T = 1/F

Question 8

define ‘frequency’

Answer 8

How many waves pass a certain point per second, measured in Hertz, Hz

Question 9

What is the equation for frequency?

Answer 9

F=1/T

Question 10

What is the equation for wave speed?

Answer 10

frequency x wavelength

Question 11

define ‘amplitude’

Answer 11

Maximum distance from the undisturbed position (ie rest to crest or trough)

Question 12

define ‘displacement’

Answer 12

The distance of a particle of the wave from equilibrium at any one time

Question 13

What is the maximum displacement of a wave?

Answer 13

The amplitude

Question 14

Which kind of graph is used to work out frequency?

Answer 14

displacement-time graph

Question 15

Which kind of graph is used to work out wavelength?

Answer 15

displacement-distance graph

Question 16

What is a radian?

Answer 16

The angle in a circle where the arc has the same length as the radius

Question 17

What is 360 degrees in radians?

Answer 17

2π

Question 18

What is 180 degrees in radians?

Answer 18

π

Question 19

What is 90 degrees in radians?

Answer 19

π/2

Question 20

What is superposition?

Answer 20

When waves in the same place pass through each other, creating a resultant amplitude at that point without affecting one another. The resultant amplitude is the sum of the two wave’s amplitudes. This can be smaller or larger than the original amplitudes.

Question 21

What are phasors?

Answer 21

A method of describing waves by showing where a wave is in its cycle, using an arrow in a circle rotating anticlockwise.

Question 22

In phasors, what does the length of the arrow represent?

Answer 22

wave amplitude

Question 23

In phasors, what does the speed of rotation represent?

Answer 23

wave frequency

Question 24

In phasors, what is one wavelength?

Answer 24

A full circle rotation (360 degrees or 2π radians)

Question 25

What is the equation for angular speed?

Answer 25

2π/t or 2πf

Question 26

What is the symbol for angular speed/frequency?

Answer 26

ω (omega)

Question 27

What is angular frequency measured in?

Answer 27

radians^-1

Question 28

What is the equation for distance traveled in radians?

Answer 28

angular frequency x time

Question 29

In a phasor diagram, what is the displacement?

Answer 29

The opposite | A x sinӨ

Question 30

What is happening when two waves are in phase?

Answer 30

There is no phase difference, waves do the same things at the same time

Question 31

What is the phase difference when waves are in phase?

Answer 31

0 or 360 degrees

Question 32

What is happening when waves are in antiphase?

Answer 32

Waves do completely opposite things at the same time

Question 33

What is the phase difference when waves are in antiphase?

Answer 33

180 degrees

Question 34

If one wave is at its maximum and one is at rest, what is the phase difference?

Answer 34

90 degrees

Question 35

What does it mean when waves are coherent?

Answer 35

Waves have the same frequency and constant phase difference

Question 36

What is the symbol for phase difference?

Answer 36

Φ

Question 37

What is a phasors position when a wave goes down through rest?

Answer 37

90 degrees pointing left

Question 38

What is a phasors position when a wave goes up through rest?

Answer 38

90 degrees pointing right