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Physics > P12/13: Waves > Flashcards

P12/13: Waves Flashcards

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1
Q

what are transverse waves and eg.

A
  • waves where points along its length vibrate 90 degrees to direction of energy transfer- travel in vacuum
  • pass through SOLIDS ONLY
    e.g. ripples in water, s-waves, electromagnetic waves
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2
Q

what are longitudinal waves and eg.

A

-waves where points along it length vibrate parallel to direction of energy transfer
-cant travel in vaccum
- PASS THROUGH SOLIDS/LIQUIDS
- e.g. sound waves
- P-waves
- pressure waves

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3
Q

what is Amplitude , symbol and measured in?

A

-distance from undisturbed position to peak/trough of wave
symbol : A
measured in : metres

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4
Q

what is wavelength , symbol and measured in?

A

distance from one point of wave to same point on next wave
symbol : lambda
measured in : metres

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5
Q

what is frequency , symbol and measured in?

A

no. waves passing a point in a second
symbol : f
measured in : Hz

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6
Q

what is time period , symbol and measured in?

A

time taken for single wave to pass a point
symbol : T
measured in : seconds

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7
Q

equation for frequency and time period?

A

f= 1/T

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8
Q

what is wave speed , symbol and measured in?

A

-distance travelled by a wave each second
symbol : V
measured in : M/S

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9
Q

WAVE SPEED EQUN

A

wave speed = f x wave length

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10
Q

laws of reflection

A
  1. angle of incidence=angle of reflection
  2. incidient ray,reflected ray and normal are all in the same plane
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11
Q

what are the least, best surfaces for relfection

A

least reflective : ROUGH SURFACES
most reflective : FLAT SURFACES

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12
Q

WHAT IS REFRACTION?

A

The change of direction in which they travelling when they cross the boundary between 1 medium to another

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13
Q

what is REFLECTION, TRANSMISSION, ABSORBTION ?

A

REFLECTION: light will reflect if object is OPAQUE /not absorbed
- smoother the surface , stronger the reflective wave
TRANSMISSION: pass through transparant material
ABSORBTION: if frequ of light macthes energy levels of electrons - light will be absorbed by electrons and not REEMITTED

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14
Q

how do soundwaves travel in the ear?

A
  • travels down AUDITORY CANAL
  • pressure of sound waves cause eardrum to VIBRATE
  • small bones connected to this also vibrate and the vibrations transfer to fluid in INNER EAR —> nerve cells detect sound
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15
Q

how does ultrasounds for medicine work?
and how does it image under surfaces?

A

measure the time between emmison and detection to show distance from source

  • imaging under surfcaes is done becuase a crack causes WAVES TO REFLECT EARLIER than the rest, so will show up
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16
Q

what is INFRASOUND?

A

sound wave that has a frequ below 20Hz: AKA seismic waves
types of seismic waves : P WAVES - long
S- WAVES - transverse

17
Q

groups of electromagnetic waves
(wavelength and frequency)

A

RADIO : 10^3 10^4
MICROWAVE: 10^-2 10^8
INFARED: 10^-5 10^12
VISIBLE: 10^-6 10^13
ULTRAVIOLET: 10^-8 10^15
X-RAY: 10^-10 10^17
GAMMA RAY: 10^-12 10^20

18
Q

for EM waves, as wavelength decreases…

shorter wavelength means smaller waves

A

frequency must INCREASE and energy of wave INCREASES

19
Q

how are radio waves produced?

A

produced by oscillations in electrical circuits
- when absorbed, create AC with same FREQUENCY AS RADIO WAVE

20
Q

hazards of UV, X-RAYS , GAMMA RAYS?

A

UV = skin ages prematurely ( skin cancer)
X-RAYS/GAMMA RAYS = ionsising radiation causing cancer /gene mutation

21
Q

uses of EM waves and why?

A

RADIO : tv, radio - LONG WAVELENGTH TRAVEL FAR WITHOUT LOSING QUALITY
MICROWAVES: satellites, cooking food - PENETRATE ATMOSPHERE TO REACH STAELLITES
INFRARED: cooking food/infrared cameras - TRANSFER THERMAL ENERGY
VISIBLE LIGHT: fibre optics - BEST REFLECTION/SCATTERING IN GLASS
UV : sun tanning, energy efficient lamps - RADIATES LEAST HEAT/MORE ENERGY
X-RAY: medical imaging and treatment /gamma - HIGH ENERGY, CAN PENETRATE MATERIAL EASILY

22
Q

what do soft tissue and bone do to xrays?

A

soft tissue: TRANSMITS
bone : ABSORBS

23
Q

why does refraction happen?

A

different mediums have different densities

24
Q

what happens when EM wave is absorbed?

A
  • can be absorbed by an electron that gives it energy
  • causes electron to move up energy level
25
Q

how is an EM emitted?

A
  • if electron moves down energy level, it emits EM wave
26
Q

how are radio waves produced in the transmitting/recieving antenna?

A

TRANSMITTING ANTENNA : charge from AC oscillates up/down antenna —> produces radio wave
RECIEVING ANTENNA: metal aerial absorbs radio waves
- creates AC with same frequnecy as transmitted wave

27
Q

what discoveries have seismic waves led to?

A
  1. on opposite side of Earth to an earthquale only P- WAVES are detected suggesting :
    - mantle is solid (both types of waves pass)
    - outer core is liquid (only P waves pass)
  2. refractions between layers cause 2 shadow zones (no p-waves detcted) suggesting:
    - inner core is solid –> due to size/positions of shadow zones
28
Q

required practical : extension

A
  1. set up apparatus of a clamp stand and spring , without any masses on the spring
  2. Align the marker to a value on the ruler, record this initial length of the spring
  3. Add the 100 mass hanger onto the spring
  4. Record the mass (in kg) and position (in cm) from the ruler now that the spring has extended
  5. Add another 100 g to the mass hanger
  6. Record the new mass and position from the ruler now that the spring has extended further
  7. Repeat this process until all masses have been added
  8. The masses are then removed and the entire process repeated again, until it has been carried out a total of three times, and an average length is calculated
29
Q

force and acceleration

A
  1. Use the metre ruler to measure out intervals on the bench, e.g. every 0.2 m for a total distance of 1 m. Draw straight lines with pencil or chalk across the table at these intervals
  2. Attach the bench pulley to the end of the bench
    Tie some string to the toy car or trolley. Pass the string over the pulley and attach the mass hanger to the other end of the string
  3. Make sure the string is horizontal (i.e. parallel to the bench) and is in line with the toy car or trolley
  4. Hold the toy car or trolley at the start point
    Attach the full set of weights (total = 1.0 N) to the end of the string
  5. Release the toy car or trolley at the same time as you or a partner starts the stopwatch. Press the stopwatch (in lap mode) at each measured interval on the bench and for the final time at 1.0 m
  6. Record the results in the table and repeat step 5 to calculate an average time for each interval
  7. Repeat steps 5-8 for decreasing weights on the weight hanger, e.g. 0.8 N, 0.6 N, 0.4 N, and 0.2 N. Make sure you place the masses that you remove from the weight stack onto the top of the car
  8. Use the distance between each interval (0.2 m) and the average time it takes for the toy car or trolley to travel that distance to calculate the average speed per interval
  9. Compare the average speed between the first and last intervals for different weights
    Use the equation below to calculate the acceleration
30
Q

INVESTIGATING wave properties

A
  1. Set up a ripple tak with a screen underneath and fill the ripple tank with water to a depth of no more than 1 cm
  2. Turn on the power supply and the light source to produce a wave pattern on the screen
  3. The wavelength of the waves can be determined by measuring length of several waves and dividing this by no. waves
  4. A stopwatch could be used - time for several waves to pass a point
    Frequency = number of waves/time
  5. Record the frequency and wavelength in a table and repeat the measurements
31
Q

what property of waves doesnt change when moving from air to glass block and why?

A

frequency
if speed and wavelength increase by same amount then frequency must stay constant

Physics (11 decks)

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