Waves Flashcards
(47 cards)
What do waves carry?
All waves carry energy.
What is the speed of sound in air?
340ms^-1
What is the speed of light in air?
(3.0x10^80)ms^-1
What is the unit for sound?
Decibels (dB)
What is frequency measured in?
Hertz (Hz)
What is the typical frequency a young person can hear?
A young person can typically hear between 20Hz to 20,000Hz.
What are frequencies above 20,000Hz called?
Ultrasound
What is “ultrasound”?
Ultrasound is any frequency above 20,000Hz
What is “frequency”?
Frequency is a measure of the number of waves per second passing a point.
What is the formula for frequency?
f = N / t
What is a “longitudinal wave”?
A longitudinal wave is one which the particles move backwards and forwards along the direction of travel.
What is wavelength measured in?
Metres (m)
What is “amplitude”?
Amplitude is the maximum distance a particle moves from it’s undisturbed point.
What is the wave equation?
v = f x [lambda]
What is the formula “v = f x [lambda] “ used for?
Calculating the speed, frequency, or wavelength of a wave.
What is a “radio wave”?
Radio waves have the longest wavelength and lowest frequency of all the waves in the EM spectrum.
Which waves have the longest wavelength in the EM spectrum?
Radio Waves
Which waves have the lowest frequency in the EM spectrum?
Radio Waves
What is a detector of radio waves?
An aerial/antenna
What speed to EM waves travel at?
All EM waves travel at the speed of light (3.0x10^8ms^-1)
What is “diffraction”?
When waves spread out around an obstacle this is called diffraction. Waves with longer wavelengths diffract more.
How can diffraction affect reception in hilly areas?
Longer wavelength, lower frequency radio waves diffract more than higher frequency, shorter wavelengths. This means longer waves can be picked up more easily in hilly areas.
What are “microwaves”?
Microwaves are part of the EM spectrum. They have a frequency of about 10GHz.
What are some sources of microwaves?
- Radar guns (police)
- Microwave oven containing a magnetron
- Mobile phone circuits (transmitted using aerial)