Waves P2 Flashcards
What do waves transfer?
Energy from one place to another but no matter
What happens to particles when a wave travels through a medium?
Particles of a medium oscillate and transfer energy between each other but overall the particles stay in the same place because only energy is transferred
Identify the 2 types of wave
Longitudinal, transverse
What is the particle motion of a transverse wave like?
Particle motion/oscillations are perpendicular to the direction of energy movement
What is the particle motion of a longitudinal wave like?
Particle motion/oscillations are parallel to the direction of energy movement
Identify 4 transverse waves
Electromagnetic waves e.g light, ultraviolet, water, s-waves (secondary)
Identify 3 longitudinal waves
Sound, ultrasound, shock waves e.g p-waves (primary)
Define amplitude
Maximum displacement of a point on the wave from its undisturbed position (half height)
Define wavelength ( symbol is lambda)
The distance between same point on two adjacent waves (e.g trough to trough)
Define frequency
Number of complete waves passing a certain point per second. Measured in hertz (1Hz is 1 wave per second)
Define time period
Time for 1 complete cycle of a wave to pass a point
Equation for frequency
Number of waves divided by time (s)
Equation for velocity of waves
frequency x lambda
Equation for time period
1 divided by frequency
Define wave speed
The speed at which energy is being transferred
What is sound?
Vibrations that travel through a medium. These are longitudinal waves because air particles vibrate along the direction of travel of the wave
Why can’t you hear anything in space?
Space is a vacuum (empty) because the air particles are so far apart that there is no medium which longitudinal waves can travel through
How does the sun’s heat reach us if space is a vacuum?
Transverse waves because they don’t need particles
Identify a factor affecting the speed of sound
The closer together the atoms (denser), the quicker sound travels
Define density
The amount of matter in a certain volume of a substance
Order glass, water, steel, air and wood from most to least dense
Steel, Glass, Wood, Water, Air
How do you make sound from a guitar louder?
Plucking strings harder because it transfers more energy
What is the amplitude of a quiet noise?
Low
What is the amplitude of a loud noise?
High
How do you make pitch higher on a guitar?
Shorten strings because it transfers energy more quickly
What is the frequency of a low pitch sound?
Low
What is the frequency of a high pitch sound?
High
What are electromagnetic waves?
Electric and magnetic disturbances which are transverse waves which transfer energy from a source to an absorber. They travel through air or space at the same speed (constant speed of light)
What is the relationship between frequency and wavelength?
Higher the frequency, shorter the wavelength
What do electromagnetic waves form?
A continuous spectrum. The wavelength and frequency boundaries are approximate as different parts are not precisely defined
identify the 7 basic types of electromagnetic waves in order of increasing frequency/decreasing wavelength
Radio waves (1-10^4m), micro waves (10^-2), infra red (10^-5), visible light (10^-7), ultraviolet (10^-8), x rays (10^-10), gamma rays (10^-15)
Which is the portion of the continuous spectrum that is visible to the human eye?
Visible light. A typical human eye responds to wavelengths from about 380-740nm and light is 400-700nm
Why are there a large range of frequencies between EM waves?
They are generated by a variety of changes in atoms and their nuclei (e.g changes in the nucleus of an atom creates gamma rays). This is why atoms can absorb a range of frequencies - each one causes a different change
Frequency of light
4.3x10^14-7.5x10^14 Hz
What are electromagnetic waves made up of?
Oscillating electric and magnetic fields
When do EM waves travel at different speeds and what can this lead to?
In different materials, can lead to refraction