P5 Flashcards
(33 cards)
What is a wave?
A wave is an oscillation that transfers energy
What are longitudinal waves (+ e.g.)?
A longitudinal wave is a wave where the direction of vibration of individual air molecules is the same as the direction of the wave. An example is sound waves
What are transverse waves (+e.g.)?
A transverse wave is a wave where the direction of vibration is at right angles to the direction of travel of the wave
Draw a diagram of a longitudinal wave and label it
see p.g. 142
Draw a diagram of a transverse wave and label it
see p.g. 142
What is amplitude, what is its symbol and what is it measured in?
Amplitude is the distance from the middle to the top or bottom of a wave. Its symbol is A and it is measured in metres or volts.
What is frequency, what is its symbol and what is it measured in?
Frequency is the number of waves per second. Its symbol is F and it is measured in Hz.
What is wavelength, what is its symbol and what is it measured in?
Wavelength is the distance from one point on a wave to the same point on the next wave. its symbol is lambda and it is measured in m
What is time period, what is its symbol and what is it measured in?
Time period is the time for one wave to pass a given point. its symbol is T and it is measured in seconds.
Draw a time trace for a wave
see p.g. 143
Draw a snapshot for a wave
see p.g. 143
How do you model transverse waves using water ripples?
As the surface of the water moves up and down, you can see that the wave travels but the water doesn’t. If you put a rubber duck on the water then it won’t move away.
How do you calculate wave velocity?
wave velocity (m/s) = wavelength (m) x frequency (Hz)
How do you model longitudinal waves using sound?
As you speak, the wave moves away from your mouth but the air doesn’t.
How do you measure the velocity of ripples?
You can use a ripple tank, and to find the wavelength you can use a flashing ‘strobe’ to freeze the waves so you can measure their length. You can then calculate the frequency by counting the number of rotations of the motor in 10s and dividing this by 10. You then use the equation to calculate velocity.
How do you measure the velocity of sound (2)?
You can time how long it takes to hear an echo of a clap when you are a distance from the wall, and use the equation linking distance, velocity and time.
You can connect a pair of microphones over a certain distance apart to an oscilloscope, which will sow the variation of pressure with time.
What are electromagnetic waves?
EM waves are transverse waves that are transmitted through space, and they all have the same velocity.
How is energy transferred in EM waves?
e.g.
EM waves transfer energy from source to absorber. E.g. sources such as the Sun have electromagnetic waves tat are absorbed by the skin.
What is the order of the main groupings of the electromagnetic spectrum?
Radio waves, microwaves, infra-red, visible light, ultraviolet, x-rays, gamma rays
This is in the order of long to short wavelength (10^2 - 10^-16)
This is in the order of low to high frequency
What can our eyes see?
Our eyes can only detect a limited range of frequencies of the electromagnetic spectrum, which is visible light
How do you produce a radio wave?
Radio waves can be produced by, or can themselves induce, oscillations in electrical circuits
What is light?
Light is an electromagnetic wave
Give examples of some practical uses of electromagnetic waves in the radio region
TV and radio stations transmit television and radio signals by adding sound and picture information to radio waves
Give examples of some practical uses of electromagnetic waves in the microwave region (3)
Your phone communicates with transmitters using microwaves. They are also used to communicate with satellites, and for wifi and bluetooth systems
Microwaves are also used in a microwave oven, where the water and fat absorb the microwaves, heating up the food
