waves

Question 1

What is a wavelength?

Answer 1

The measurement of crest to crest.

Question 2

What is an amplitude?

Answer 2

An amplitude is the maximum number of displacements in the oscillation cycle.

Question 3

What is displacement?

Answer 3

How far the quantaty that is in oscillation has moved from its mean?

Question 4

What are examples of transverse wave?

Answer 4

Electromagnetic waves and water ripples.

Question 5

Example of a longitudinal wave?

Answer 5

Sound wave

Question 6

What does the number of different displacement particles along the same direction along which the wave is propagating lead to?

Answer 6

It can cause compression and rarefactions which means the particles are close together and the wave are further apart.

Question 7

What are longitudinal waves know for and why?

Answer 7

Pressure waves because the compression(particles close together) and the rarefractions(waves further apart) leading to changing speed.

Question 8

what is superposition?

Answer 8

When the waves are in phase and they travel in same place and same time.

Question 9

What happens when an electron moves down an energy level?

Answer 9

It becomes deexcited and releases photonic energy in the form of light.

Question 10

What happens when an electron moves up an energy level?

Answer 10

Gets excited and absorbs photon energy light. The smaller the gaps which are at the highest energy level will produce a low frequency but a longer wavelength wave, the less the frequency the less the energy and so the plain the colour.

Question 11

How is a wave formed?

Answer 11

The wave displaces from the equilibrium.

Question 12

How is a stationary wave formed?

Answer 12

A stationary wave is formed by the wave displacing from the equilibrium. Then the
wave is in incidence and travels towards the boundary. Then the other wave travels away from the boundary and is superposed with the other wave and so they are inphased and so this leads to constructive inteference. Then as both the waves keep moving they alternate between in phase and out of phase. Out of phase causes them to be destructive inteference and this causes the waves to be stationary. Then the node is a fixed point along the boundary. Antinode is formed from constructive inteference.

Question 13

What is refraction?

Answer 13

When light changes direction when hitting the boundary or when changing mediums.

Question 14

What is total internal reflection?

Answer 14

When a light wave is flowing from a slow medium to a fast medium and then turns away from the normal for a while and then just stops. The incidence ray is then bigger than the critical angle. When it is incidence in the fibre optics cable then the incoherence light is sent down the endoscope and hits the object and then comes back up as coherence which produces a clear image of the object.

Question 15

What is an analogue signal?

Answer 15

A signal that has different frequencies and amplitude can vary.

Question 16

What is a digital signal?

Answer 16

A digital signal is made up of binary bits and has only one amplitude.

Question 17

Factors that affect quality of adc?

Answer 17

The sampling rate and the sampling sensitivity.

Question 18

What is sampling rate?

Answer 18

How many samples per second.

Question 19

What is sampling sensitivity?

Answer 19

How close together the samples are.

Question 20

Advanatages of digital signals?

Answer 20

Carry a lot of information in the same bandwith.
Can easily filter out inteferences because it can recognise it easier. Computer memory and processing is digital.

Question 20

How is an image converted into digital signal?

Answer 20

Split up into different picture elemens or pixels. And each pixel has a binary code. The pixels are too small so we cant usually see it.

Question 21

Disadvantages of digital signals?

Answer 21

It can take time to process the signal. It depends on the sampling rate,sampling sensitivity ect.

Question 22

What do communication satellited do?

Answer 22

They recieve signals from ground stations.
Transmit them over a wide area. They use frequency from 1 to 400GHz.

Question 23

Why is the uplink and downlink frequency different?

Answer 23

So that they dont intefer with each other.

Question 24

What does the transponder do in a satelite when they recieve a signal?

Answer 24

Recieve it, filter it,amplify it and transmit it using a new frequency.

Question 25

What does a mobile phone do?

Answer 25

It has its own transmitter that recieves and send signals. This is frequencies from 800MHZ to 2.6Ghz. They all networked together and the network covers the whole country.

Question 26

What is a network?

Answer 26

A network is a group of devices linked together. A network may be wired which uses cables or wireless e.g bluetooth or wifi. Devices in a wifi network is connected to a local hub or router in a range of 10mm. Both wifi and bluetooth operate at a frequency at a 2.6Ghz.

Question 27

What is bluetooth?

Answer 27

Bluetooth does not need to connect to wifi as it can communicate. The range of bluetooth is 10m. Devices that use batteries use bluetooth as its power needs are low. Bluetooth can allow music and speech but is not good for high quality videos as it does not carry the same information required for that as wifi does.

Question 28

What is infrared?

Answer 28

Eg. a tv remote, have a range of just a few metres and need a clear sight of line to work. Infrared has a high frequency but the information is sent as pulses . The frequency of infrared is 40Khz.

Question 29

What type of mouthpiece is important and how for the fundamental frequency?

Answer 29

Flute and oboe behave like an open end. The mouthpiece will affect fundamental frequency and harmonics produced.

Question 30

What does a differaction grating do?

Answer 30

Measures the wavelength of the elements and the different colours.

Question 31

What is a wavelength?

Answer 31

The distance between the adajacent particles oscilatting in phase.