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G9 + 10 physics > unit 3 - waves > Flashcards

unit 3 - waves Flashcards

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1
Q

Waves

A

disturbances created in a medium which transfers energy and momentum from one point to another, cant tranfer matter

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2
Q

Propogate

A

To travel

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3
Q

In waves, what do particles do>

A

They dont move, they just oscillate and vibrate , tranansferring the wave from one particle to another, and sometimes get reflected

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4
Q

what happens to medium in waves

A

remains static

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5
Q

Types of waves based on requirement of meidum to travel

A

Electromagnetic and Mechnical waves

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6
Q

Electromagnetic waves

A

Waves which do not require a medium to propoagte. Wave in which the electrical field and the magnetic field mutually oscillate perpendicular to the propagation of the wave\

Eg = Light waves

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7
Q

Mechanical waves

A

Waves which require medium to travel

eg = Sound waves, water ripples, seismic waves

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8
Q

Types of waves based on movement of particles

A

Transverse and Longitudinal

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9
Q

Transverse waves

A

Propogation of particle is perpendicular to the direction of propogation of energy, particles oscillate up and down

eg = em waves and light waves

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10
Q

Longitudanal Waves

A
  1. Vibration of particles in the medium is parallel to the direction of propagation of wave

It looks likes particles are moving left to right but they come back to their mean position

Eg - sound waves, waves produced in a slinky

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11
Q

Compression

A

Area in longitudnal waves where the particles are close to each other, the area where density and pressure are higher than normal

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12
Q

Rarefaction

A

Area in a longitudnal wave where the particle are far apart from each other, the area where density and pressure are less than normal

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13
Q

4 characterstic properties of waves

A
  1. wavelength
  2. amplitude
  3. frequency
  4. Wave velocity
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14
Q

Wavelength (transverse)

A

Distance between two consecutive troughs or crests

Si unit = mtr

Symbol = Lambda

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15
Q

wavelength (longitudanal)

A

measure distance between 2 consecutie compressions or rarefaction

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16
Q

Amplitude

A

Maximum displacement of a particle from its mean position in the positive or negative direction

si unit = mtr

symbol = A

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17
Q

Frequency and how to calculate it from diagram

A
  • No. of disturbances/waves per unit time
  • No. of oscillations per unit time
  • Si unit = Hertz (Hz)
  • 1 Hz = 1 wave per second
  • To calculate frequency, we can also count the number of waves (from crest to crest or trough to trough) in a one second diagram
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18
Q

Wave velocity with formula

A
  • distance a wave travels per unit of time
  • Also known as Phase velocity
  • Symbol = V
  • Si unit = ms^-1
    formula = lambda times frequency
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19
Q

Time period

A

Time taken to complete one full oscillation
Si unit = sec
formula = T = 1/f

20
Q

Wave equation

A

Speed = Freuqney times wavelength
Frequency = speed/wavelength
Wavelength = speed/frequency

21
Q

Wave phenomenons

A
  1. Reflection
  2. Refraction
    1. Total internal reflection
  3. Dispersion
  4. Diffraction
22
Q

Ray

A

direction in which a wave propogates

23
Q

reflection

A

A phenomenon in which a wave bounces back into the same medium after being incident on a reflection surface

24
Q

laws of relfection

A
  1. The incident ray, the reflection ray and the normal to the reflecting surface must lie on the same plane
  2. The angle of incidence must be equal to the angle of reflection
25
Q

point of inciencde

A

The point on a surface at which the incident ray hits/strikes and causes phenomenon like reflection and refraction

26
Q

Refraction

A
  • For refraction, the wave must travel must rarer to denser medium

Change in speed of a wave when passing from one medium to another

  • Change in direction of motion
  • Frequency does not change!
  • Angel of incidence increases = Angle of refraction also increase
27
Q

bending of refracting ray - denser to rarer

A

Away from normal

28
Q

Bending of refracting rray - rarer to denser

A

towards the normal

29
Q

Laws of refraction

A
  1. The incident ray, the refracting ray and the normal to the surface or separation at the point of incidence must lie on the same plane
  2. Snells Law: The ratio of sine of angle of incidence and the sine of angle of refraction for a given pair of media is always constant and is called the refractive index of the second medium with respect to the first medium
30
Q

formula for snells law

A

sin i/ sin r = n2/n1 = v1/v2

31
Q

Total internal reflection

A
  • when a wave propogates from a denser to rarer medium, TIR (total internal reflection) takes place
  • Speed increase in TIR
  • Refracted ray bends away from normal
  • In TIR, 100% of the wave is reflected
32
Q

conditions for total internal relfection

A
  1. Incident ray must travel from denser to rarer medium
  2. ∠i must be greater than the critical angle
33
Q

critical angle

A

Angle of incidence for which the corresponding angle of refraction is 90°

34
Q

diffraction

A

Phenomenon in which a wave spreads whenever it comes across an obstacle or a slit, provided the size of the slit or the obstacle in comparable to the wavelength of the wave

35
Q

dispersion

A
  • Phenomenon in which a polychromatic light splits into its monochromatic constituents

Higher the wavelength, lesser the deviation

eg = white light splitting into vibgyor colour

36
Q

basic cause of dispersion

A

refraction multiple times

37
Q

reflection of sound

A

echo

38
Q

electromagnetic spectrum (decreasing order of wavelength)

A

Radio waves
Micro waves
Infra red radiation
Visible light spectrum
Ultra violet rays
X rays
Gamma radiation

39
Q

Infra red radiatiom

A

Electromagnetic radiation which gives us the feeling of warmth. Any value above absolute 0 (O kelvin) will give IRR

40
Q

How the wavelength of Infra red radiations determined

A

by temperature and doesnt have one set value

41
Q

why is there no unit for refractive index

A

ratio of sines of 2 speeds and since sines have no unit, this also doesnt have any unit

42
Q

sound waves

A
  • Type of mechanical wave
  • Type of longitudanal wave
  • They can be described as patterns/sequence of disturbance created in space-time which compress and expand the air around it to create disturbances which are known as sounds
43
Q

what is pitch in sound waves

A

Frequency of sound waves

Higher frequency = higher pitch

44
Q

which medium do sound waves travel the best

A

They can travel in fluids but travel best in solids to due Prescence of closely packed molecules

45
Q

What happens in Echo location (specifically for bats)

A

Animals like bats scream high frequency sounds and these waves reflect of animals, objects and low pressure regions and then using a bats sense of sound, he is able to use these reflection to paint a picture of his surroundings and find out the exact speed, size, direction, and location of these objects

46
Q

Where is echo location used by humans

A

In SONAR and radar systems

47
Q

Absorption in waves

A

When a wave transfers its energy onto a material it passes through, causing the material’s atom and molecules to vibrate

G9 + 10 physics (6 decks)

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