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 Author: mardiellen ID: 197237 Filename: Science Updated: 2013-02-01 20:40:39 Tags: Optics Energy Electro wave prop Oscillation Electricity Errors Folders: Description: science Show Answers:

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1. Systematic Errors
Errors which follow certain physical and mathematical rules and therefore we can correct
2. What reduces Systematic Errors
- Calibrate instruments carefully before field work starts

- Design and use suitable measurement routines and procedures

- Correct measurement results afterwards
3. Gross Errors
Can be of any size or measure and are due to human mistakes, malfunctioning equipment or wrong measurement methods.
4. What reduces Gross Errors
- Surveyors carefulness in procedures

- Relentless checking of work
5. Random Errors
Errors which behave randomly and effect the measurement in a non-systematical way
6. What reduces Random Errors
- Is the total measurement conditions have been improved

- Statistical procedures
7. Curvature & Refraction Error
- Refraction of light rays through the Earth's atmosphere causes an object to seem higher than it really is in most cases

- Curvature of the Earth's surface causes an object to appear lower than it really is
8. What reduces Curvature & Refraction Errors
- Not using the bottom 50cm of the Tachstaff
9. Precision
Is the measure of Repeatability
10. Accuracy
Is a measure of Reliability
11. Treatment of errors
- Constant and systematical errors are eliminated by observational procedures

- Periodic and Random errors are eliminated where possible, and then their effect is reduced by repetition
12. Potential Difference
Is a measurement of the amount of energy it would take to move an object from one place to another
13. Electric Current
The movement of electrons to a point of high voltage to a point of low voltage
14. Direct Current
Flows continuously in a circuit in one direction only
15. Ohm's Law
• States that, in an electrical circuit, the current passing through a conductor between the two points is proportional to the potential difference
•                            V
•       ohm's law      I/R

• V= Voltage
• I= Amps
• R= Ohm's
16. Resistance
- Resistance is a measure of the degree to which an object opposes an electrical current through it

- The unit for electrical resistance is OHM Ω
17. Electric Power
- Is defined as the rate at which electrical energy is transferred by a circuit

- The unit for electric power is Watt
18. Parallel Batteries
19. Series Batteries
20. Alternating Current
Is where the direction of the flow of electrons switches back & forth at regular intervals
21. Purpose of a Transformer
- A device which transfers electrical current form one circuit to another through a shared magnetic field

- It steps up or down a current
22. 5 Layers of the Atmosphere
• - Troposphere
• - Stratosphere
• - Mesosphere
• - Thermoshere
• - Exosphere
23. Effect of F1 & F2 layers on magnetic propagation
- The F region is a very anomalous layer within the Ionosphere. Is important for HF wave propagation

- F1 layer is good for reflecting medium wave frequencies. Is only there during the day

- F2 layer is used for long range Shortwave communications. Is there day and night
24. 3 types of Electromagnetic Wave Propagation
- Skywave: the propagation of radio waves bent back to the Earth's surface by the Ionosphere (HF radio)

- Groundwave: propagates by interacting with the semi-conductive surface of the Earth. (Radio, Local TV)

- Direct or Line of Sight Waves: refer to electromagnetic waves travelling in a line of sight. They are blocked by obstructions and cannot travel over the horizon. (Wi-fi, bluetooth)
25. Electromagnetic Spectrum
Is the range of all possible frequencies of electromagnetic radiation
26. Effect of Atmospheric Humidity on Electromagnetic Propagation
The water in the air refracts, scatters and absorbs the electromagnetic waves.
27. Ray model of Light
The line of travel taken by light
28. Natural Light
The visual light reflected from solar radiation
29. Reflection
The light from a single incoming direction is reflected in a single outgoing direction

eg. reflection of a mirror
30. Refraction
Occurs when light rays travel from one medium with a given refractive index to a medium with another

eg. light travelling from air to water
31. Diffraction
The bending, spreading and interference of waves passing by an object or aperture which disrupts the waves

eg. waves hitting a break wall, the halo the sun makes around clouds
32. Dispersion
es the spatial seperation of a white light into spectral components of different wavelengths

eg. Rainbows
33. 3 types of lenses & what effect do they have on light
- Convex Lenses: when light travels parallel to the lens axis and passes through the convex lens it will be converged to a spot on the axis

- Concave Lenses: when a parallel beam of light passes through a concave lens the rays of light are diverged

- Compounding: are a combination of simple lenses which have 2 or more lenses on the same axis
34. Magnifying Power & Magnification
- Magnifying Power is the process of enlarging something only in appearance, not in physical size

- Magnification is a number describing which factor an object is magnified
35. Crosswires
A reference scale placed into an optical instrument
36. Field of View & Apparent Field of View
- FofV:The angular extent of the observable world that is seen at any given moment

- AFofV: A derived constant value for a given eye piece used to calculate the field of view
37. Periodic Motion
Any motion that repeats itself and can be expressed mathematically
38. Period
An interval of time between the recurrence  of phases wave form
39. Frequency
The number of waves to pass a fixed place in a given amount of time
40. Amplitude
The measurement of the degree of charge (+/-) in atmospheric pressure caused by sound waves
41. Simple Harmonic Motion
Is an oscillatory periodic motion that is neither driven or damped
42. Modulated Oscillation
Is the results of the process, whereby some characteristic of a wave or oscillation is varied in accordance with the characteristics of another wave
43. Composite Oscillation
Is the resultant wave motion of a particle where there is more than one force acting on it
44. Constructive & Destructive Interference
- If a crest of a wave meets a crest of another wave at the same point then the crests interfere constructively & the resultant wave amplitude is greater.

- If a crest of a wave meets a trough of another wave then they interfere destructively, & the overall amplitude is decreased
45. Forced Oscillations
When an oscillating system may be subject to some external force in order to prevent damping
46. Wave Theory
• Is a distortion in a material or medium, where the individual parts of the material only show periodic motion, but the wave form itself moves through the material
• Longitudinal Wave- the particle displacement is parallel to the direction of wave propagation (sound)
• Transverse Wave- the particle displacement is perpendicular to the direction of the wave propagation (light)
47. Standing Waves
Two waves with the same frequency wave length & amplitude travelling in opposite directions will interfere and produce a standing waves
48. Vibrations
The mechanical oscillation about an equilibrium point

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