Chapter 5.2 - Wave phase and superposition

Question 1

What Is the cycle of one complete wave measured as

Answer 1

2Pie

Question 2

What are wavefronts?

Answer 2

Lines connecting points on the wave that are at exactly the same phase position

Question 3

What are wave fronts?

Answer 3

Lines connecting points on the wave that are at exactly the same phase position

Question 4

What is constructive interference

Answer 4

The superposition effect of two waves that are in phase producing a larger amplitude resultant wave

Question 5

What is destructive interference?

Answer 5

The superposition effect of two waves that are out of phase producing a smaller amplitude resultant wave

Question 6

What is wave superposition

Answer 6

When waves meet each wave tries to cause a wave displacement at the point of intersection according to their phases at that location.

The net effect is that the overall displacement is the vector sum of the displacements caused by the individual waves.

Question 7

What is a ray?

Answer 7

The ray indicates the direction of propagation of wave while the wavefront is the surface of constant phase

Question 8

What are stationary/standing waves?

Answer 8

A wave that consists of oscillations in a fixed space with regions of significant oscillation and regions with zero oscillation which remain in the same locations at all times.

Question 9

What does coherent mean In terms of waves?

Answer 9

Waves are called “coherent” if they have the same frequency and have a constant phase relationship

Question 10

What is a progressive wave?

Answer 10

A means for transferring energy via oscillations

Question 11

What are nodes?

Answer 11

Regions on a stationary wave where the amplitude of an oscillation is zero

Question 12

What are antinodes

Answer 12

Regions on a stationary wave where the amplitude of oscillation is at its maximum

Question 13

What is a sonometer

Answer 13

A piece of apparatus for experimenting with the frequency pf relationships of a string under tension, usually consisting of a horizontal wooden sounding box and a metal wire stretched along the top of the box

Question 14

Why don’t stationary waves stick to the strict definition off a wave?

Answer 14

They don’t transfer any energy

Question 15

String wave speed equation

Answer 15

v= square root of : Tension in string / mass per unit length

Question 16

The fundamental frequency in a string equation

Answer 16

( 1 / 2xLength of string) X (SR of Tension in string / mass per unit length)

Question 17

What is wave diffraction?

Answer 17

When a wave passes the edge of an obstacle the wave energy spreads into the space behind the obstacle.

Question 18

What factors affect diffraction?

Answer 18

Size of the obstacle and the wavelength of the wave

Question 19

Describe the diffraction pattern observed when light passes through a narrow slit

Answer 19

Central maxima, areas of darkness (destructive interference ((out of phase)), decreasing intensity.

Question 20

What does the sum of displacement between 2 waves = if no light can be seen?

Answer 20

Total displacement = 0

Question 21

What is the observations of narrowing the slit in a single slit diffraction?

Answer 21

Wider maximum, further maxima and minima

Question 22

What is a diffraction grating?

Answer 22

A device that will cause multiple diffraction patterns which then overlap creating an interference pattern with a mathematically well-defined spacing between bright and dark spots

Question 23

Equation for a diffraction grating?

Answer 23

wavelength x the order = diffraction spacing x sin (angle between original direction and the direction of a bright spot)

d must be in millimetres or metres for metres do 1/number per metre for millimetres do (1x10^-3)/number per mm

Question 24

What is interference

Answer 24

The superposition outcome of a combination of waves. An interference pattern will only be observed under certain conditions such as coherent waves

Question 25

What are the qualities of coherent waves

Answer 25

Same frequency

Constant phase relationship

Question 26

What happens in the two slit experiment

Answer 26

Two waves are brought together to produce an interference pattern.

Question 27

What is two-slit interference

Answer 27

Two-slit interference is a form of two-source intereference where the slits diffract existing waves to act as new sources of waves.

Question 28

What is wave refraction?

Answer 28

Change in wave speed when the wave moves from one medium to another. There is a corresponding change in wave direction (Governed by snells law)

Question 29

What is the refractive index of wave?

Answer 29

The measure of the amount of refraction caused by different materials

Question 30

What is the refractive index equation

Answer 30

n can be defined in several ways but is fundamentally a result of change in wave speed…

refractive index = speed of light in vacuum/ speed of light In medium

Question 31

What is snells law

Answer 31

n1 X sinx1 = n2 X sinx2

n=refractive index of material x= angle that the ray makes to the normal to the interface between the two media at the point the ray meets that interface

Question 32

critical angle formula

Answer 32

sin x = n2/n1

Question 33

Critical angle equation for light emerging into air

Answer 33

sin x = 1/n1

Question 34

What is the critical angle

Answer 34

The largest angle of incidence that a ray in a more optically dense medium can have and still emerge into the less dense medium. Beyond this point the ray will be totally internally reflected

Question 35

What is total internal reflection?

Answer 35

All wave energy is reflected inside the more dense medium.

Question 36

Requirements for total internal reflection

Answer 36

The ray attempting to emerge from more dense medium

The angle between the ray and the normal to the interface is the greater than the critical angle