# Physics Unit 1 section 1

Mind Map by soniamartinelli1, updated more than 1 year ago
 Created by soniamartinelli1 about 6 years ago
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### Description

Mind Map on Physics Unit 1 section 1, created by soniamartinelli1 on 01/25/2014.

## Resource summary

Physics Unit 1 section 1
1 Waves
1.1 Frequency
1.1.1 Number of vibrations per second
1.2 Wavelength
1.2.1 Length of one whole wave
1.3 Amplitude
1.3.1 Maximum displacement (height)
1.4 Period
1.4.1 Time taken for a whole vibration
2 Electromagnetic spectrum
2.1 RMIVUXG
2.2 Microwaves
2.2.1 Used in mobile phones
2.2.2 Carry signal containing texts
2.3 Infrared waves
2.3.1 Used in heat cameras
2.3.2 Carries signal from remote to TV
2.4 Visible light
2.4.1 Used in scientific imaging
2.4.2 Image can be recorded electronically
3 Useful equations
3.1 Frequency = 1/time period
3.2 Speed = wavelength X frequency
4 Transverse waves
4.1 Vibrations at right angles to direction
4.2 All EM waves are transverse
5 Polarisation
5.1 Waves only oscillate in one direction
5.2 Polarising filter stops wave going up and down and side to side
6 Converging lenses
6.1 Change curvature of wavefronts
6.1.1 By refraction
6.3 Slows down light at center of lens for longer than at edges
6.4 More powerful lens = more curved wavefronts = shorter focal length
6.5 Power = 1/Fl
7 Lens Equation
7.1 1/v = 1/u + 1/f
7.1.1 v = lens to image u=lens to object f=focal length
7.2 Distant source u = 0
7.3 Magnification = v/u
8 Binary number system
8.1 Only uses two digits 0 and 1
8.1.1 Numbers make up binary digits
8.1.2 One binary digit = a bit
8.1.3 8 bits = a byte
8.2 Used to store data on a computer
8.2.1 Saved as a string of bits
8.2.2 Number of bits in a string determines how many alternatives it can code for
8.2.2.1 1 bit = 2 alternatives 1 byte = 256 alternatives
8.2.2.2 Doubles with each bit
8.2.2.3 No. alternatives = 2^No. of bits
8.2.2.4 No.bits = log2^(No. alternatives)
9 Images
9.1 Array of binary numbers
9.1.1 Each pixel = 1 binary number
9.1.2 Value gives colour of square
9.2 Noise
9.2.1 Unwanted interfearance
9.2.2 Replacing value with mean of 8 around it reduces noise
9.3 Can be manipulated to alter image
10 Sampling
10.1 Analogue signals vary continuously
10.1.1 Over range of loudness/freq.
10.2 Electronic signals
10.2.1 Will pick up noise
10.2.2 Details are lost when reconstructed
10.2.3 Easier to reconstruct digital as there are less values
10.3 Digitising
10.3.1 Analogue can be digitised
10.3.1.1 Samples taken at regular intervals
10.3.1.2 Find nearest digital value
10.3.1.3 Quality depends on: resolution and sampling rate
10.3.1.4 Higher resolution = better match
10.4 Resolution = possible digital values
10.4.1 Big number of bits = good resolution
10.5 Noise
10.5.1 Limits amount of bits per sample
10.6 Sampling rate
10.6.1 Minimum = 2 X max frequency
11 Signals
11.1 Made up of lots of different frequencies
11.2 Band width: highest frequency - lowest frequency
11.3 Bits per sec (rate of transmission) = bits per sample X samples per second
12 Digital/Analogue
12.1.1 Can be sent/received/reproduced more easily
12.1.2 Resistant to noise
12.1.3 Used to represent different information
12.1.4 Easy to produce using computers
12.2.1 Can never reproduce analogue completely accurately
12.2.2 Some info always lost