Flashcards
Physics
Cards in this deck (17)
- 1Does a wave carry matter or energy? Which direction does a wave move? What are the 4 wave properties? What are the units for; Displacement, amplitude, wavelength, period, frequency, phase difference?Energy
Away from the source
Diffraction, interference, reflection, refraction
m, m, m, seconds, hertz, degrees/radians - 2What is reflection? What is refraction? What is diffraction?A wave bounces back when it hits a boundary.
A wave changes direction as it enters a different medium.
Waves spread out as they go through a narrow gap or round an object. - 3Give examples of a Transverse wave What direction do the vibrations in a Transverse wave travel?Electromagnetic wave + ripples.
Perpendicular to the direction of travel. - 4What is a polarised wave? What type of wave can be polarised? How can waves be polarised? What happens when light is reflected? Uses...A wave that only oscillates in one direction.
Transverse.
Through a polarising filter which only lets light travel in one direction.
It is partially polarised.
TV, Radio, Satellites, Bees, CD players etc. - 5What happens to wavefronts when they pass through a convex lens? Is there a difference in the time taken to reach the focal point? What happens to the curvature as the power increases?They are refracted and curvature is added because the middle of the wave slows down for longer.
No, all of the wavefront reaches it a the same time.
The curvature increases. - 6What is a Bit? What is a Byte? What uses Bits/Bytes as memory storage? In a picture what is 1 pixel represented by? In imaging, what does a binary number give?A single Binary Digit.
8 Bits.
A computer.
A Binary Number.
The colour (or shade of grey) - 73 ways to process images? How are digital signals represented?Mean Smoothing,
Edge Detection,
Median Smoothing.
Binary numbers - 8What and how do all electronic signals pick up when transmitted? What eliminates reconstructs a signal best (analogue or digital)? Why?Noise (interference), from electrical disturbances.
Digital, the number of vales the signal can take is limited. - 9How can analogue signals be digitised? What is the negative of digitisation?Take the value of the signal at regular time intervals and find the nearest digital number. Each digital value is represented by a binary number.
Won't be exactly the same as the analogue. - 10What factor effect how well a digital signal matches the original? How is resolution determined?1. Resolution(difference between the possible digital values) 2. Sample rate (time between each sample)
Number of bits in the binary number representing the digital values. ( bits ^ , resolution^) - 11What limits the number of bits used for sampling? What is the ratio? What is the minimum sampling rate?Noise.
Total variation in the signal : variation caused by noise.
Twice the maximum frequency. - 124 advantages of digital signals compared to analogue signals1. Can be sent, received and reproduced easier because they can only take a limited number of values 2. Resistant to the effects of noise 3. Can be used to represent different types of information in the same way.images and sound)
4. Easy to process using to computers. - 13What are the frequencies that make up a signal called? What is bandwidth? How is bandwidth calculated? How is bandwidth used for communications systems?Spectrum.
The range of frequencies within a signal.
Highest freq. - lowest freq.
how many signals can be sent at the same time. - 14How are communication signals transmitted?By carrier waves.
- 15How does your radio receive sound?1.audio signal converted to electrical signal which is mixed with a carrier wave and transmitted
2.when the radio is tuned to the right freq. it receives the signal and separates the actual signal from the carrier wave.
3.actual signal is converted back into audio waves - 16What is the size gap between freqs. determined by? what is the disadvantage of gaps between carrier signals?Bandwidth (larger bandwidth, larger gap to stop interference)
Limits the number of signals that an be transmitted - 17Rate of transmission= ___1___ x___2___samples per second x bits per second
1. at least 2x highest frequency so all freqs are transmitted.
2. high enough that the transmitted signal closely matches original, but not too high that it is affected by noise
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- Flashcards on Physics, created by Rachel OLIVER1935 on 03/02/2015.
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- Rachel OLIVER1935
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