waves (p2) Flashcards
What is a transverse wave?
Transverse waves oscillate perpendicular to the direction of energy transfer
What is a longitudinal wave?
Longitudinal waves osciallate parallel to the direction of energy transfer
What is an example of a transverse wave?
Water waves (ripples)
What is the difference between longitudinal and transverse waves?
Longitudinal waves oscillate parallel to the direction of energy transfer.
Transverse waves oscillate perpendicular to the direction of energy transfer.
What is an example of a longitudinal wave?
Sound waves
Are water ripples examples of a transverse or a longitudinal wave?
transverse
Is sound an example of a transverse or a longitudinal wave?
longitudinal
What is the definition for the amplitude of a wave?
the maximum displacement of a point on a wave away from its undisturbed position
What is the definition for the wavelength of a wave?
the distance from a point on one wave to the same point on the next wave
What is the definition for the frequency of a wave?
the number of waves passing a point each second
What is the definition for the time period of a wave?
the time taken for a wave to complete one full oscillation
What is the equation that links time period and frequency of a wave?
Period = 1 Γ· frequency
What is the unit for time period?
seconds s
What is the unit for frequency?
Hertz, Hz
What is the equation that links wave speed, wavelength, and frequency of a wave?
wave speed = frequency x wavelength
What is the unit for wave speed?
metres per second, m/s
What is the unit for wavelength?
metres m
Describe a method to measure the speed of sound waves in air
Make a loud noise on a field near a wall, and use:
- a measuring tape to measure the distance to and from the wall;
- and a stopwatch to measure the time for the echo of the noise to be heard.
Use the equation speed = distance Γ· time to calculate the speed
Describe a method to measure the speed of ripples on water
Set up a ripple tank and use:
- a ruler to measure wavelength;
- and a stopwatch to measure frequency.
Use the equation wave speed = frequency x wavelength to calculate the speed
What are electromagnetic waves?
transverse waves that transfer energy from the source of the waves to an absorber
What are the waves on the electromagnetic specturm, in order from longest to shortest wavelength?
Radio, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays
Which part of the electromagnetic spectrum transfers the most energy?
Gamma rays
Which part of the electromagnetic spectrum has the shortest wavelength?
gamma rays
Which part of the electromagnetic spectrum has the highest frequency?
gamma rays
Which part of the electromagnetic spectrum has the longest wavelength?
radio waves
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] What happens to a light ray when it enters an object that is more optically dense?
It bends towards towards the normal
Which part of the electromagnetic spectrum has the smallest frequency?
radio waves
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] What happens to a light ray when it enters an object that is less optically dense?
It bends towards away from the normal
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] What causes refraction of waves?
the difference in the velocity of the waves in different substances
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] What four possibilities could happen when a wave goes through a substance?
different substances may reflect, transmit, absorb or reflect electromagnetic waves in ways that vary with wavelength
What happens when a wave refracts?
changes direction
What type of surfaces are good at absorbing and emitting raditation?
Dark, matte (dull) coloured surfaces
What type of surfaces are good at reflecting radition?
Bright, shiny coloured surfaces
Explain why refraction takes place as a wave moves from one substance to another
Refraction takes place because waves will travel at different velocities in different substances
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] How can radio waves be produced?
by oscillations within electric circuits
[ππΆπ΄π΅π²πΏ π§πΆπ²πΏ] What happens when radio waves are absorbed by an electrical conductor?
they create an alternating current with the same frequency as the radio wave itself
How can gamma rays be produced?
by changes in the nucleus of an atom
Which types of waves can have hazardous effects on body tissue?
ultraviolet waves, X-rays and gamma rays
What is radiation dose (in Sieverts) a measure of?
the risk of harm resulting from an exposure of the body to the radiation
What are the risks of ultraviolet waves on body tissue?
they can cause skin to age prematurely and increase the risk of skin cancer
What are the risks of X-rays and gamma rays on body tissue?
they are ionising radiation that can cause the mutation of genes and cancer
What are uses of radio waves?
Television and radio
What are uses of microwaves?
Satellite communications, cooking food
What are uses of infrared?
Electrical heaters, cooking food, infrared cameras
What are uses of visible light?
Fibre optic communications
What are uses of ultraviolet?
Energy efficient lamps, sun tanning
What are uses of X-rays?
medical imaging and treatments (e.g. treating cancer)
What are uses of gamma rays?
medical imaging and treatments (e.g. treating cancer)
