Chapter 11 Wave Properties Flashcards
What is a wave and what can it be used for
A wave is a means of transfering energy from one place to another without a transfer of matter between the two points
You can also use waves to transfer information mobile phone,radio
What’s a mechanical wave and examples
vibrations that travel through a medium (a substance):
Sound waves, water suface waves
What’s an electromagnetic wave and examples
all travel through a vacuum at the speed of 300,000 km/s. No medium is needed
Light waves, radio waves and microwaves
Whats a transverse wave
The direction of oscillation of a wave is perpendicular ( 90° ) to the direction of motion of the wave. All EM waves are transverse waves.
What’s longitdunal waves
The direction of oscillation of a wave is parallel to the direction of motion of the wave.
What type of waves are mechanical waves
They can be transverse or longitdunal
What is the amplitude of a wave
Amplitude - the maximum displacement of a point of a wave from its rest position
What is the frequency of a wave
Frequency - the number of waves passing a point each second
What is the period of a wave
Period - the time taken for a full cycle of the wave, usually measured from peak to peak, or trough to trough
What is the wavelength of a wave
Wavelength - distance covered by a full cycle of the wave, usually measured from peak to peak, or trough to trough
Period equation
T = 1/f
Period = 1 / frequency (Hz)
Frequency equation
F = 1/T
Frequency(Hz) = 1 / T
The wave equation
V = f x wavelength
Velocity (ms^-1) = freuency (Hz) x wavelength(m)
What is displacement -(meausred in metres) in a wave
The change in posistion of an object
How to measure speed of sound in air(calculation)
Speed = distance / time taken
How to measure wave properties experiment 1 (ripple tank and water waves) - step by step
1.-Set up the apparatus as shown 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 using a ruler to measure the length of the
screen and dividing this distance by the number of wavefronts
4.-The frequency can be determined by timing how long it takes for a given number of waves to pass a particular point and dividing the number of wavefronts by the time taken
5.-Record the frequency and wavelength in a table and repeat the measurements
How to measure wave properies experiment 2 (strings and masses)
1-Set up the apparatus as shown, then adjust the frequency of the signal generator until a “solid” wave is produced
2.-Once the “solid” wave is produced, record the frequency shown on the signal generator
3.-Use a ruler to measure the wavelength, the length to measure will depend on the number of “solid” waves produced. Or measure the length of multiple wavelengths, and divide by the number of wavelengths seen
4.-Repeat the procedure by adjusting the frequency until another “solid” wave is produced
Ray diagram
What is the bottom bar?
Line going through middle?
Left angle?
Left ray?
Right angle?
Right ray?
1-boundary
2-the normal
3-angle of incident
4-ray of light or incident ray
5-angle of reflection
6-reflected ray
Why does light change direction ( truck example)
A truck changes direction as it slows down
Light is refracted when it slows down
Waves are refracted when they slow down
What is refraction
when a wave changes direction as it changes speed when it passes from one medium to another. So the wavelength change as well but the frequency remain unchanged.
What happens after waves go through deep water to shallow water
Speed is less in shallow water. So edge of wave front entering shallow water slows down but the part of the wave front in deeper water continues at a higher speed leading to a change direction of the wave fronts
What else happens to objects when it’s hit by light (not reflected or refracted)
Absorbed or transmitted
