# Physics revision

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1. What is meant by the time periiod of a wave?
The time taken for a source to complete one wave.
2. What is the Wavelength?
• The distance from one point of the wave to next i.e crest to crest or trough to trough
3. What is the frequency of a wave?
• F = 1/T
• or
• no. of waves produced per second
4. What is the amplitude?
The maximum displacement from resting position. on the graph it looks like like the maximum point above the line. DO NOT CONFUSE THIS for the distance between the very top bit and the very bottom bit.
5. What is the formula to find refractive index
n = sin i / sin r

• where n = refractive index
• i= angle of incidence
• r = angle of refraction
6. What is the formula for the critical angle, and what is it actually?
sin c = 1/ n

The point where the angle of refraction = 90 degrees
7. What is the role of the moderator in a fission reaction?
Slows down neutrons to make them more easily absorbable by Ur 235.
8. What is the role of the control rods?
Absorb neutrons and take them out of the fission process completely
9. What is the nature of an electric current in a metal wire?
Movement of free electrons from negative to positive
10. How do molecules (e.g in a gas) exert a force?
Very many collide at high speeds into the walls of the container
11. Why are transformers used?
• To increase voltage for transmission
• So energy losses are less/system more efficient/less energy lost As heat/transmission current is small
• To decrease voltage to safer value for use in homes etc.
 Author: keesukim ID: 146282 Card Set: Physics revision Updated: 2012-05-23 06:25:14 Tags: revision Folders: Description: Physics concepts / formulae that I keep forgetting Show Answers: