Chapter 11 - Properties of Waves Flashcards
What are waves?
waves are a means of transferring energy from place to place
Does this slinky represent a longitudinal or transverse wave?
Transverse
Does this represent a transverse or longitudinal wave?
Longitudinal
What is a transverse wave?
- One that oscillates at right angles to the direction in which the energy or wave is moving
Name an example of a transverse wave
- light waves
- waves travelling on the surface of water
What is a longitudinal wave?
- A longitudinal wave is one in which the oscillations, are along the direction in which the energy or wave is moving
Name an example of longitudinal wave
Sound waves
Label:
a) Peak
b) Trough
c) Wavelength
d) Amplitude
What is the amplitude?
- Maxiumum movement of particles from their resting position caused by a wave
What is the wavelength?
- Distance between a particular point on a wave and the same point on the next wave
What is the frequency?
- Number of waves produced each second by a source
- Or the number passing a particular point each second
What is frequency measured in?
Hertz (Hz)
What is the period?
- The time it takes for a source to produce one wave
what is the equation for frequency?
1
__________________
time period (s)
what is the equation for time period?
1
frequency
Calculate the period of a wave a frequency of 200 Hz
T = 1 / frequency
= 1/200
= 0.005
= 5 ms
What is the equation for wave speed?
frequency x wavelength
A tuning fork creates sound waves with a frequency of 170 Hz. If the speed of sound in air is 340 m/s, calucate the wavelength of the sound waves
wave speed = frequency x wavelength
340 = 170 x wavelength
340 = 170 x 2
= 2m
Explain how a ripple tank works (6 points)
- Motor is turned on
- Wooden bar vibrates
- Creating a series of ripples on the surface of the water
- Light placed above the tank creates patterns
- Patterns of the water waves on the floor
- We can see how water waves are behaving through patterns
In reflection, the angle of incidence is ……. to the angle of reclection
equal
what happens to a wave when they strike a concave barrier?
- they become curved and are made to converge
what happens to waves when they strike a convex barrier?
- they are made to diverge
What is refraction?
- When waves change speed they change direction, when they cross a boundary between two substances with different densities
What is an example of refraction?
waves through glass and air
What is diffraction?
the process by which a beam of light or other system of waves is spread out as a result of passing through a narrow aperture or across an edge, typically accompanied by interference between the wave forms produced.
Example of diffraction around an edge
radio waves that are diffracted as they pass over hills
When light reflects from the surface of a plane mirror, the angle of incidence is ………………… the angle of refraction
equal to
Calculate the wavelength (2)
- number of waves/cycles = 3.5
- 0.60 = 0.17 (m)
The wavelength of a wave is 0.17m. Calculate the frequency of this microwave. [speed of microwave in free space = 3x10 to the 8 m/s²]
wave speed = frequency x wavelength
wave speed / wavelength = frequency
3x10 to the 8 / 0.17 = 1.8x10 to the 9
1.8x10 to the 9 Hz
Name the effect shown by the radio waves in diagram 1 (1)
- Diffraction
Suggest why this effect is not shown by the microwaves in diagram 2 (2)
- microwaves not diffracted as much
- diffraction (only seen) when size of barrier/gap comparable to wavelength
- radio-waves have (much) longer wavelength than microwaves/RA;
