Waves & The EM Spectrum Flashcards
(18 cards)
What do waves transfer?
Waves transfer energy and information without transferring matter.
How do we know it is the wave that moves, not the medium (water or air?
A floating object on water bobs up and down but doesn’t move forward with the wave. Similarly, air particles vibrate in place when sound travels.
What is frequency and what is wavelength?
Frequency (f) = number of waves per second (Hz)
Wavelength (λ) = distance between two crests or troughs (m)
What do amplitude, period, and wave velocity mean?
Amplitude = maximum displacement
Period (T) = time for one wave
Velocity (v) = speed at which wave travels
What is the difference between longitudinal and transverse waves?
Longitudinal: particles vibrate parallel (e.g., sound, seismic P-waves)
Transverse: particles vibrate perpendicular (e.g., light, water, seismic S-waves)
What are the two equations for wave speed?
v = frequency x wavelength
v = distance/time
How do you measure wave speed?
Sound in air: measure distance and time (clap and echo method)
Water ripples: use strobe light to freeze motion and ruler to measure wavelength
What is tested in the wave speed practical?
Measure wave speed using equipment like signal generators, vibration generators, microphones, and ripple tanks.
Measure frequency and wavelength to calculate wave speed.
What happens when a wave is refracted?
It changes direction and speed when entering a different medium due to a change in wave velocity.
What can happen to waves at a boundary?
a) Reflection – wave bounces back
b) Refraction – wave bends
c) Transmission – wave passes through
d) Absorption – wave energy is taken in
How does wave behaviour depend on the material and wavelength?
Different materials can reflect, absorb, transmit or refract differently depending on the wavelength of the wave.
What happens to velocity, frequency and wavelength when a wave changes medium?
Velocity changes
Wavelength changes
Frequency stays the same
How are sound waves converted in solids?
a) Vibrations cause particles in solids to move, producing sound
b) Only works in a limited frequency range (e.g., human hearing range)
How does the human ear detect sound?
Sound waves vibrate the eardrum, passing through bones and cochlea, converting vibrations into electrical signals for the brain.
How can you calculate depth or distance with waves?
depth = (speed of sound x time) / 2.
What is ultrasound?
Sound with a frequency above 20,000 Hz
What is infrasound?
Sound with a frequency below 20 Hz
Name uses of ultrasound and infrasound.
Ultrasound: foetal scanning, sonar
Infrasound: detecting earthquakes, exploring Earth’s core
