Waves 1

5.0(1)
studied byStudied by 9 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/46

flashcard set

Earn XP

Description and Tags

Made with help from @beanny3004's flashcards: https://knowt.com/flashcards/7e598737-637e-4f97-ac54-0b748931397a

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

47 Terms

1
New cards

Progressive wave

A wave in which oscillations/ wave fronts (or peaks & troughs / compressions & rarefactions) move through the medium as energy is transferred

2
New cards

Displacement

distance from the equilibrium position in a particular direction; a vector, so it can have either a positive or a negative value

3
New cards

Amplitude

Maximum displacement from the equilibrium position (can be positive or negative)

4
New cards

Wavelength

minimum distance between two points in phase on adjacent waves, for example, the distance from one peak to the next or from one compression to the next

5
New cards

Period of oscillation (time period)

the time taken for one oscillation or time taken for wave to move one whole wavelength past a given point

6
New cards

Frequency

The number of oscillations per unit time

7
New cards

Wave speed

the distance travelled by the wave per unit time

8
New cards

Wave speed equation

v = fλ

wave speed = frequency x wavelength

9
New cards

Releationship between frequency and time period

f = 1/T

10
New cards

Phase

The position of a certain point on a wave cycle, (units are radians, degrees or fractions of a cycle)

11
New cards

Phase difference

  • How far ‘out of step’ the oscillations at two points on the same wave or similar waves

  • Difference is normally measured in degrees/radians, but sometimes in fractions of a cylce or wavelength

12
New cards

Transverse wave sketch (include the direction of oscillations, the direction of energy transfer, equilibrium position, wavelength, amplitude and peak & trough)

<p></p>
13
New cards

Longitudinal wave sketch (include the direction of oscillations, the direction of energy transfer, equilibrium position, wavelength, amplitude and compressions & rarefactions)

knowt flashcard image
14
New cards

Transverse wave

A wave in which oscillations (of medium particles) are perpendicular to the direction of energy transfer

15
New cards

Longitudinal wave

A wave in which oscillations of the medium particles are parallel to the direction of energy transfer

16
New cards

Describe the difference between longitudinal and transverse waves.

  • In a transverse wave oscillations are perpendicular to the direction energy transfer

  • In a longitudinal wave oscillations are parallel the direction of energy transfer

17
New cards

Range of wavelengths of radio waves

10-1 to >106 metres

18
New cards

Range of wavelegnths of microwaves

10-3 to 10-1 metres

19
New cards

Range of wavelengths of infrared radiation

7×10-7 to 10-3 metres

20
New cards

Range of wavelengths of visible light

4×10-7 to 7×10-7 metres

21
New cards

Range of wavelengths of ultraviolet

10-8 to 4×10-7 metres

22
New cards

Range of wavelengths of x-rays

10-13 to 10-8 metres

23
New cards

Range of wavelengths of gamma rays

<10-16 to 10-10 metres

24
New cards

Diffraction

The spreading out of a wave front as it passes through a gap or around an obstacle. Maximum _____ will occur when the gap the wave passes through is the same size as the wavelength of the incident wave

<p>The spreading out of a wave front as it passes through a gap or around an obstacle. Maximum _____ will occur when the gap the wave passes through is the same size as the wavelength of the incident wave</p>
25
New cards

Reflection

The change in direction of a wave at a boundary between two different media, so that the wave remains in the original medium

26
New cards

Law of reflection

The angle of incidence is equal to the angle of reflection

27
New cards

Refraction

The change in direction of a wave as it changes speed (due to its change wavelength) when it passes from one medium to another

28
New cards

Law of refraction

n1sin(θ1)=n2sin(θ2)

29
New cards

Snell’s law

n sin(θ) = k

where n is the refractive index of material, θ is the angle between the normal and the incident ray, and k is a constant

30
New cards

In phase

When particles are oscillating perfectly in step - they have 0 phase difference

31
New cards

In anti-phase

When particles are oscillating completely out of step - they have a phase difference of πc / 180o

32
New cards

Refractive index

n = c/v, where n is the _______ of the material (it has no units), c is the speed of light through a vacuum (3.00 x 108ms-1), and v is the speed of light through the material in ms-1; how much a material slows down light - is a ratio

33
New cards

Critical angle

  • The angle of incidence at the boundary between two media that will produce an angle of refraction of 90°

  • Sin(C)=1/n

34
New cards

Total internal reflection

The reflection of all light hitting a boundary between two media back into the original medium when the light is travelling through the medium with the higher refractive index and the angle of incidence at the boundary is greater than the critical angle

35
New cards

Conditions required for TIR

  • The light must be travelling through a medium with a higher refractive index as it strikes the boundary with a medium with a lower refractive index.

  • The angle of incidence must be above the critical angle. This angle depends on the refractive index of the medium.

36
New cards

Intensity

____ is the power transmitted per unit area: I = P / A = P / (4πr2)

37
New cards

What is the relationship between intensity and amplitude?

Intensity is proportional to amplitude2: I ∝ A2

38
New cards

Electromagnetic wave

  • Transverse wave with oscillating electric and magnetic field components at right angles to each other

  • They don’t need a medium to propogate

  • They have a speed of 3×108ms-1 in a vacuum

39
New cards

Electromagnetic spectrum

full range of frequencies of EM waves, from gamma rays to radio waves

40
New cards

Wave profile

displacement-distance graph of a wave (‘snapshot’ of the wave)

41
New cards

Unpolarised wave

Transverse wave in which the oscillations occur in many planes

42
New cards

Partially polarised wave

  • Transverse wave in which there are more oscillations in one particular plane, but the wave is not completely plane polarised

  • Occurs when transverse waves reflect off a surface

43
New cards

Plane polarised wave

Transverse wave in which the oscillations are limited to only one plane - convention is to use the electric field

44
New cards

Polarisation (transmission) axis

The axis (direction) which waves are allowed through

45
New cards

How a polarising filter works

  • Contains many long chain molecules that are aligned in the same direction

  • The molecules absorb light aligned in that direction

  • Therefore the orientation of the molecules is PERPENDICULAR to the polarisation axis. Diagrams usually show the polarisation axis - DO NOT CONFUSE THE TWO

46
New cards

Describe how you can use a polarising filter to determine if a beam of light is polarised. State clearly what you should observe.

  • Rotate the polaroid

  • Look for dim / bright light

  • Alternating every 90°

47
New cards

How does changing the wavelength affect diffraction

Assuming the wavelength is still comparable to the size of the gap:

  • Shorter wavelength means less diffraction

  • Longer wavelength means more diffraction, until the wavelength is greater than or equal to the gap. After this it diffracts the same amount