Waves And Oscillation 2 Flashcards

1
Q

Define superposition (1)

A

-the combination of 2 or more waves to form a resultant wave

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2
Q

State the principle of superposition (2)

A

-the resultant displacement is the vector sum of the individual displacement due to each other
-when 2 waves are of small or big amplitude, they either cancel out or add up

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3
Q

Define phase (1)

A

-the measurement of the position of a certain point along the wave cycle

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4
Q

Define standing waves (1)

A

-a standing waves is the superposition of 2 progressive waves with the same frequency, wavelength p and amplitude in the opposite direction

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5
Q

Define progressive waves (1)

A

-is a type of wave that Carrie’s energy from one place to another through a medium

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6
Q

Define nodes (1)

A

Points where the amplitude of the wave is zero

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7
Q

Define anti node (1)

A

Where the amplitude is maximum

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8
Q

Define monochromatic light (2)

A

-source of light which have the same frequency and wavelength
-always in phase

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9
Q

State general ideas about the single slit diffraction (3)

A

-the central fridge is twice as wide as each other the outer fringes
-each of the fringes is the same width
-the outer fringes are less intense than the central fringe

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10
Q

Why is monochromatic coherent sources used in diffraction (3)

A

-needed to view fringes with different wavelengths or to see young’s fringes clearer
-so you get the same diffraction
-longer wavelengths bend more

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11
Q

Define central maximum (2)

A

-it is the point with the greatest intensity
-central maximum is the result of waves from all the slits aligning at a certain angle due to constructive interference

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12
Q

Why is the central maximum the brightest (2)

A

-intensity of light is highest at the centre
-increase in intensity means an increase in number of photons emitted per second

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13
Q

What happens if wavelength increases, state in terms of intensity and diffraction (2)

A

-increases amount of diffraction
-central maximum is lowered

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14
Q

What happens if slit width increases, state in terms of intensity and diffraction (2)

A

-decreases amount of diffraction
-intensity of central maximum is higher

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15
Q

What happens if slide width is narrower , state in terms of intensity and diffraction (1)

A

-makes the fringes wider

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16
Q

State the formula involving angle at which wave forms (1)

A

n x wavelength = slit spacing x sinO

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17
Q

Define white light (2)

A

-it is a mixture of different colors
-each having different wavelengths

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18
Q

What is observed when white light is shone through a single slit (2)

A

-all of the different wavelengths are different by different amounts
-red diffracting the most and it has the greatest wavelength but lowest frequency

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19
Q

What color is the central maximum when white source is used and why (2)

A

-it’s white
-because it results from the combination of all the colors in the white light spectra

20
Q

State the formula for fringe spacing (1)

A

Fringe spacing = ( distance from slit to screen x wavelength ) / spacing between slits

21
Q

Define and explain constructive interference (5)

A

-when the wave pulses combine, the resulting pulses have an amplitude equal to the sum of the amplitude of the individual pulses
-Crest + crest gives a bigger crest
-when they are perfectly aligned together they are in phase
- path difference = wave1 - wave2 = whole number of wavelength
-when they’re out of phase path difference is decimals

22
Q

Define path difference (1)

A

-distance travelled by the 2 waves from their source to the point where they meet

23
Q

State and explain the concept of destructive interference (5)

A

-when 2 or more waves come together and their individual pulses combine in a way that reduces or cancels out their amplitudes
-crest + trough of equal size gives us nothing as 2 displacements cancel out each other
-they are in anitphase
- path difference = wave1 - wave2 = decimal wavelength
-when they’re out of phase the path difference is a whole number

24
Q

State an application of destructive interference when in phase (2)

A

-noise canceling earphones
-the headphones cancel out the sound by sending in their own sound by opposite phase which cancels out the noise effect

25
Q

What happens if the single slit is too wide in two source interference (4)

A

-it can make the interference pattern less clear
-because the single slit let’s through a lot of light which can weaken the effects of interference
-the dark fringes will become narrower than the bright fringes so contrast is lost
-if the single slit is too wide you might not even see the interference pattern at all

26
Q

What should you do to get a good interference pattern (1)

A

-use a single slit that’s narrower or similar in width

27
Q

How are fringes formed in two source interference (6)

A

-due to the interference of light from the 2 slits
-when lights from the 2 slits super pose
-lights from the 2 slits is coherent
-bright fringes = constructive interference (in phase)
-dark fringes = destructive interference (out of phase
-central is white fringe

28
Q

How are bright fringes formed (4)

A

-where the waves overlap constructively
-when a leak from one wave aligns with the peak of another wave they superpose each other
-the light waves from each slit arrive in phase with each other
-at points where constructive interference occurs , the amplitude of waves add up giving maximum intensity so there is more energy concentrated hence brighter fringe

29
Q

How are dark fringes formed (3)

A

-the light from one slit cancels the light from the other slit
-waves overlap in a way that their peaks align with their troughs leading to destructive interference
-and a point of minimum

30
Q

Define fringe spacing (1)

A

-the distance from the centre of a bright fringe to the centre of the next bright fringe

31
Q

What does the equation fringe spacing = (wavelength x distance from slit to screen) / slit spacing tell you ? (3)

A

-the distance from slit to screen is increased
-the wavelength of the light used is increased
-the slit spacing is reduced

32
Q

What are the safety precautions needed when using a laser (3)

A

-wear safety goggles
-never shine a laser towards a person
-don’t shine on reflective surface

33
Q

What is the law of reflection (2)

A

-the angle of incidence is equal to the angle of refraction
-when light reflects, a phase change can occur depending on refractive indexes of each medium

34
Q

When does refraction occur (1)

A

-it occurs when light passes a boundary between 2 different transparent media

35
Q

What does refraction occur due to (4)

A

-different speeds:
Light travels at different speeds in different material

-bending of light:
When light enters s denser material, it slows down and changes direction

36
Q

What happens when light travels from air to glass (3)

A

-less dense ti more dense
-light bends towards the normal
-angle of incidence is greater than angle of refraction

37
Q

What happens when light travels from glass to air (3)

A

-more dense to less dense
-light bends away from the normal
-angle of refraction greater than angle of incidence

38
Q

What are the properties that change during refraction (2)

A

-speed
-wavelength

39
Q

Define refractive index and state its formula (2)

A

-it is a property of a material which measures how much light slows down when passing through it

N = speed of light / speed of light in substance

40
Q

What is the speed of light. (1)

A

3 x 10^8

41
Q

What is the refractive index of air (1)

A

1

42
Q

State the formula of snells law (1)

A

N1 x sinOi = N2 x sinOr

43
Q

When does total internal refraction occur (4)

A

-angle of incidence is greater than the critical angle
-n1 > n2
-as the angle of incidence increases, the angle of refraction also increases until it gets closer to 90 degree
-when the angle of refraction is exactly 90, light is refracted along the boundary

44
Q

What are the conditions required for TIR (2)

A
  • n1> n2
    -angle of incidence greater than critical angle
45
Q

State formula for critical angle (1)

A

Sin 0c = n2 / n1

46
Q

State the meaning of coherent sources (3)

A

-same phase difference
-same wavelength
-same frequency