Waves - Basics - Chapter 15

Question 0

What is a progressive wave?

Answer 0

A wave that carries energy from one place to another.

Question 1

What is the position that an oscillation vibrates about?

Answer 1

The equilibrium position or mean position.

Question 2

What is a mechanical wave?

Answer 2

A wave that travels through a medium.

Question 3

SUD of wavelength?

Answer 3

S - lambda
U - m
D - the distance between two adjacent points that are in phase.

Question 4

SUD of period?

Answer 4

S - T
U - s
D - time taken for one complete oscillation of a point in a wave.o

Question 5

SUD of frequency?

Answer 5

S - f
U - Hz (seconds power -1)
D - the number of oscillations of a particle per unit time.

Question 6

SUD of displacement?

Answer 6

S - x bar (mean of x)
U - m
D - distance of any part of the wave from the mean position (can be + or -).

Question 7

SUD of amplitude?

Answer 7

S - A
U - m
D - the maximum displacement of a wave from it’s mean position (positive only).

Question 8

SUD of phase difference?

Answer 8

S - O with a line through it
U - rad
D - the fraction of a cycle between the oscillations of two particles, expressed in degrees.

Question 9

Define intensity?

Answer 9

The power transmitted normally through a surface per unit area.

Question 10

Intensity equation?

Answer 10

I = power/unit area
(w/m2) = (W)/(m2)
I is proportional to the square of the amplitude (inverse square law).

Question 11

What is a pure wave?

Answer 11

Smooth wave, no jagged edges.

Question 12

What is a regular wave?

Answer 12

Set wavelength and set amplitude.

Question 13

Power = ?

Answer 13

E(J) / t(s).

Question 14

Examples of transverse waves?

Answer 14

Water waves, s-waves, EM waves.

Question 15

What is a transverse wave?

Answer 15

A wave where the displacement is perpendicular to the direction of the wave.

Question 16

What is a longitudinal wave?

Answer 16

A wave where the displacement is parallel to the direction of the wave (pressure waves).

Question 17

Examples of a longitudinal wave?

Answer 17

Sound waves, p-waves, wind instrument.

Question 18

What is an impure wave?

Answer 18

A wave with jagged edges.

Question 19

What is an irregular wave?

Answer 19

A wave with a random line (unpredictable amplitude and wavelength).

Question 20

When measuring phase difference, what is 360 degrees?

Answer 20

2pi radians

Question 21

What is 180degrees when measuring phase difference?

Answer 21

1pi radians

Question 22

Speed of a wave = ?

Answer 22

Frequency (1/time) x wavelength

f x lambda

Question 23

What is path difference?

Answer 23

The difference in the distances travelled by two waves from coherent sources at a particular point.

Question 24

Define refraction?

Answer 24

The change in direction of a wave as it crosses an interface between two materials where it's speed changes. Frequency doesn't change!

Question 25

Intensity equation 2?

Answer 25

Intensity= Power / cross sectional area

Question 26

What is speed of propagation, and if it changes how is this shown on a displacement position graph?

Answer 26

It is the speed at which a wavefront passes through a medium, relative to the speed of light. It will not affect a displacement position graph?

Question 27

Define diffraction?

Answer 27

The spreading of a wave when it passes through a gap or past the edge of an object.

Question 27

Define reflection?

Answer 27

The bouncing back of a wave from a surface.

Question 28

Define coherent?

Answer 28

Two sources are coherent when they emit waves with a constant phase difference.

Question 29

Define antinode?

Answer 29

A point on a stationary wave with maximum amplitude.

Question 30

Define dispersion?

Answer 30

The splitting of light into its different wavelengths.

Question 31

Define electromagnetic spectrum?

Answer 31

A family of waves that travel through a vacuum at a speed of 3.0x10^8 m/s.

Question 32

Define power?

Answer 32

The rate at which energy is transferred or the rate at which work is done.

Question 33

Define rarefaction?

Answer 33

A region in a sound wave where the air pressure is less than the mean value.

Question 34

Define wave?

Answer 34

A periodic disturbance travelling through space, characterised by vibrating particles.

Question 35

How are water waves refracted?

Answer 35

Water waves are refracted when the depth of the water changes. Shallower water means the waves travel slower than deeper water.

Question 36

Page 165?

Answer 36

Diagram on reflection.

Question 37

How high frequencies can the human ear detect?

Answer 37

20Hz to 20kHz

Question 38

Angle of reflection =

Answer 38

Angle of incidence