waves

Question 1

Transverse Waves

Answer 1

A type of wave in which the particles oscillate at right angles to the direction the wave travels

Question 2

Longitudinal Wave

Answer 2

A type of wave in which the particles oscillate parallel to the wave direction

Question 3

wavelength / lambda

Answer 3

the distance between two matching points on neighbouring waves. in metres

Question 4

amplitude

Answer 4

the maximum displacement a point moves from the centre of oscillation. in metres

Question 5

amplitude in comparison to energy

Answer 5

the larger the amplitude, the greater the energy of the wave

Question 6

Period

Answer 6

the time taken for a point on a wave to move through one complete oscillations. in seconds

Question 7

Frequency

Answer 7

any wave is the number of oscillations per second measured in hertz

Question 8

frequency equation

Answer 8

f = 1 / T

Question 9

Mechanical waves

Answer 9

required a medium for transmission and are generated by vibrating sources

Question 10

electromagnetic waves

Answer 10

are created when charged particles are accelerated. They require no medium for transmission

Question 11

Maxwells conclusion

Answer 11

• maxwell found that the speed of the em waves would travel at a speed c = 1/ eu
• light must be an em wave as its same as his answer
• maxwell predicted that waves must also exist with frequencies much bigger and much smaller than light in a continuous spectrum

Question 12

what did hertz demonstrate + discover

Answer 12

demonstrated - reflected, refracted and polarised
discovered - radio waves

Question 13

Experiments with radio waves

Answer 13

• by placing a sheet of metal between the transmitter and detector he showed that radio waves are reflected by metal
  he discovered that insulators do not absorb radio waves by placing his detector in another room
  he strengthened his beam by placing a concave reflector around it

Question 14

x-rays

Answer 14

had a wavelength of the order 10^-10
electrons emit x rays after high speed collisions or through a high energy transition in an atom
in space, x rays come from very hot stars of from charged particles accelerated to enormous speeds
x rays are produced by making high speed electrons collide with a metal target

Question 15

EM Waves properties

Answer 15

1) travels at the speed of light
2)can be reflected, refracted and polarised
3)Show interference and diffraction effects
4) can travel through a vacuum
- Different frequencies interact with matter in very different ways

Question 16

What is interference in physics?

Answer 16

Interference occurs when two or more waves meet and their amplitudes combine either constructively or destructively, resulting in changes in the overall wave pattern.

Question 17

what is constructive interference?

Answer 17

when two waves are in phase and the amplitude increase when interfere

Question 18

Destructive intefarance

Answer 18

180 degrees out of phase therefore trough is inligned with peak causing there to be no amplitude

Question 19

What conditions are necessary for constructive interference?

Answer 19

Constructive interference occurs when waves meet in phase, meaning their peaks and troughs align, and their path differences are whole multiples of the wavelength.

Question 20

What conditions are necessary for destructive interference?

Answer 20

Destructive interference occurs when waves meet out of phase, meaning their peaks align with troughs, and their path differences are odd multiples of half the wavelength.

Question 21

What is phase difference?

Answer 21

Phase difference is a measure of how “in step” or out of step two waves are with each other. It’s usually measured in degrees or radians

Question 22

How is phase difference represented mathematically?

Answer 22

Phase difference (ϕ) can be calculated using the formula: ϕ = (2π / λ) × path difference, where λ is the wavelength of the wave.

Question 23

the principle of superposition

Answer 23

Where two or more waves meet, the total displacement at any point is the sum of the displacements that each individual wave would cause at that point

Question 24

refraction definition

Answer 24

when light travels from one transparent material to another it changes direction . This happens because the light changes velocity

Question 25

What happens when light goes from a less dense material to a more dense

Answer 25

The light slows down and bends towards the normal.

Question 26

What happens when light goes from a more dense material to a less dense

Answer 26

The light speeds up and bends away from the normal.

Question 27

What is Snell's Law

Answer 27

sin i / sin r = 1n2 ( refractive index). It has no units. also v1/v2 and lamba1/ lamba 2. Wavelength changes as the wave moves from one material to another

Question 28

definition of the absolute refractive index

Answer 28

The absolute refractive index of a material is the refractive index for light travelling from a vacuum into that material

Question 29

what can 1n2 be shown as

Answer 29

n2/n1 = sin1 / sin2 which is rearranged into n1sin1=n2sin2

Question 30

absolute index in terms of speed

Answer 30

c(speed of light in a vacuum) / Vs( speed of light in substance)

Question 31

usage of stationary waves

Answer 31

detecting leakage in pipeline systems x rays standing wave for calibrating commercial and reference attenuators.

Question 32

Definition of a node

Answer 32

A point along a standing wave with 0 amplitude

Question 33

antinode

Answer 33

a point along the wave with maximum amplitude

Question 34

What is the distance between a node and an antinode

Answer 34

a quater of a wavelength

Question 35

Definition of a stationary wave

Answer 35

when two waves having equal amplitude and frequency moving in opposite direction along the same line. Waves formed by the reflected wave.

Question 36

what is a harmonic

Answer 36

a stationary wave can only be produced at resonant frequencies, however there will be more than one for each length of string. These are called harmonics.

Question 37

Difference between stationary and progressive waves

Answer 37

1. each point along a progressive wave as equal amplitude, but for a stationary wave the amplitude varies 2. adjacent points on progressive waves vibrate with different phase but all particles between nodes in stationary waves vibrate in phase 3.Energy is transferred through space in progressive waves but not in the case of stationary waves.

Question 38

velocity of a wave in a string

Answer 38

v= root T/u (mass per unit length)

Question 39

Equation for the fundamental frequency of a string

Answer 39

lamba =2l f1= v/2l

Question 40

General equation of a string

Answer 40

Fn= nv/2l

Question 41

Fundamental frequency in a closed pipe

Answer 41

v=4 lamba f1= v/4l

Question 42

general equation for a stationary wave in a closed pipe

Answer 42

fn= nv/4l

Question 43

what is an overtone

Answer 43

An overtone is any resonant frequency above the fundamental frequency of a sound.

Question 44

Fundamental frequency in an open pipe

Answer 44

lamba = 2l f1= v/2l

Question 45

General equation for stationary waves in an open pipe

Answer 45

lamba = 2l fn = nv/2l

Question 46

state the equation used to calculate intensity

Answer 46

I = P/A Power/Area

Question 47

What is the refractive index of a material through which light travels a speed of v?

Answer 47

n= c/v where c is speed of light in vacuum

Question 48

state the equation linking the refractive indexes and angles at an interface between two mediums

Answer 48

n1sino1= n2sino2

Question 49

what is the critical angles

Answer 49

the angle of incidence which the angle of refraction is 90 degrees and all the light passes along the boundary between the mediums. Beyond this angle all light will be reflected

Question 50

state the equation used to calculate a critical angle

Answer 50

sinc = 1/n

Question 51

what is total internal reflection

Answer 51

total internal reflection is where all the light is reflected back at the boundary between two mediums. It occurs when light is incident at an angle greater than the criticle angle

Question 52

what is the focal point of a converging lens

Answer 52

the single point where the parrallel rays of light entering the lens converge to

Question 53

what is the focal length of a lens

Answer 53

the distance between the centre of the lens and the focal point

Question 54

what is the equation used to calculate the power of a lens

Answer 54

power = 1/ focal length

Question 55

How do you calculate the total power of a combination of thin lens

Answer 55

p = p1 + P2 + ..

Question 56

what is a real image

Answer 56

a real image is one that can be projected onto a screen and is always inverted. real images are the consequence of light meeting at a focal point.

Question 57

what is a virtual image

Answer 57

virtual images are the consequence of rays of light appearing to meet a point. they cannot be projected onto a screen.

Question 58

state the equation used to calculate the magnification of an image

Answer 58

magnification = image height / object height

Question 59

What is plane polarisation?

Answer 59

Plane polarisation is when the oscillations of a wave are restricted to a single plane