Science physics revision Flashcards

1
Q

What is a progressive wave

A

A wave that transfers energy from place to another without transferring material

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2
Q

What is amplitude

A

maximum displacement from rest position

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3
Q

What is wavelength

A

The distance between two matching points on neighbouring waves

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4
Q

What is frequency

A

The number of waves that pass in a certain amount of time

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5
Q

What is a transverse wave

A

The oscillations are perpendicular to the direction of wave travel

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6
Q

What is a longitudinal wave

A

The oscillations are parallel to the direction of wave travel

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7
Q

What is the equation to calculate wave speed

A

frequency times wavelength

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8
Q

What is a stationary wave

A

A wave that travels in opposite directions and this requires the same frequency but different constant phase

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9
Q

What is the phase difference of constructive difference

A

0

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10
Q

What is the phase difference of destructive interference

A

180

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11
Q

Describe bright spots

A

It has constructive interference, maximum amplitude and the peak meets with a peak and it has a phase difference of 0

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12
Q

Describe dark spots

A

It has destructive interference, minimum amplitude, the peak meets with a through and the phase difference is 180

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13
Q

What is refractive index

A

The ratio of the speed of light in a vacuum compared to the speed of light in a material

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14
Q

What is the calculation to calculate refractive index

A

n=c over v

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15
Q

What are the requirements for total internal reflection

A

The angle of incidence has to be greater than the critical angle and n1 has to be bigger than n2 ( more dense to less dense)

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16
Q

What is excitation

A

When the electrons absorb the wave as light and they jump up levels

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17
Q

What is dexecitation

A

The electrons fall back down to their ground energy level and they release energy as light

18
Q

What is the distance of the first harmonic

A

4m

19
Q

What is the distance of the second harmonic

A

2m

20
Q

What is the distance of the third harmonic

A

1.5m

21
Q

describe satellite communications

A

higher power signals over very long distances by dish antennae.

22
Q

what are the advantages of satellite communications

A

it can provide higher bandwidth and broadcasting possibilities
it can offer fast and reliable transmission
it enables wireless and mobile communcation applications

23
Q

Describe bluetooth

A

lower power device to device links range up to 10m, the frequency is about 2.4 to 2.485

24
Q

What are the advantages of microwaves

A

they can pass through the ionosphere
has better satellite communication
has a higher bandwitdth

25
Q

What are the disadvantages of microwaves

A

transmission is affected by fog and rain
cannot communicate with vessels underwater
can be only be used in a line of sight

26
Q

what are the advantages of radiowaves

A

can reach receivers out of site of the transmitter
can reflect off the ionosphere

27
Q

what are the disadvantages of radiowaves

A

low bandwitdth
cannot carry as much information
it is also subject to interference

28
Q

what are the advantages of digital signals

A

signals can be regenerated so is there is no loss of information
signals can carry more information because the signal is more multiplexed
there is less energy wasted because of total internal reflection

29
Q

what are the disadvantages of digital signals

A

they are easily damaged because they are so fragile and brittle
poor joints lead to poor signal strength so the signal is poor
information can be scrambled because of sampling errors

30
Q

what are the advantages of the analogue signal

A

it is best fitted for audio and video transmission
it posesses higher density
its easier in processing

31
Q

what are the disadvantages of the analogue signal

A

data can be corrupted in analogue signals
it is quite difficult to synchronize an analogue sound
it also posess lower quality than digital

32
Q

what are the advantages of infrared

A

does not interfere with other devices as the frequency is higher than bluetooth
has better quality and communication between devices due to higher frequency

33
Q

what are the disadvantages of infrared

A

needs a line of sight
works with one device at a time
sunlight will interfere with the signal

34
Q

what are the advantages of bluetooth

A

does not need to be in direct line of sight
bluetooth can be used on more than one device at the same time

35
Q

what are the disadvantages of bluetooth

A

low bandwidth

interference with other bluetooth devices on similar radio frequencies if close by

36
Q

what are the similarities between bluetooth, mobile phones and wifi

A

The frequencies of all each are all in the same range
All the frequencies are in microwave
Wifi and mobile phones networked

37
Q

What are the differences between bluetooth, wifi and mobile phones

A

wifi allows for wider communication
Wifi range is average house
mobile phones transmitters are high powered

38
Q

How do fibre optics work?

A

transfer information using pulses of light. Each pulse undergoes total internal reflection down the fibre optic cable. The core must be as transparent as possible to prevent any attenuation. Cladding is used to protect the core to prevent cross over between cables. This allows for total internal reflection to take place. It must have a lower refractive index index than the the core.

39
Q

True or false, waves in a string use longitudinal waves?

A

False, they use transverse waves

40
Q

What things need to be changed in wave of a string?

A

The tension, the length, and the mass per unit length needs to be changed in a transverse wave

41
Q

What things need to be changed in a wave of a pipe?

A

The air pressure, and the length of air columns using stops

42
Q

What are the similarities between waves in a string and waves in a pipe?

A

Both of them use oscillations and vibrations
Both use stationary waves and standing waves
Both produce sound due to resonance