# Physics Definitions

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1. Transverse Waves
• The direction of oscillation of a particle is perpendicular to the direction of propagation of the wave.
• Eg. electromagnetic waves such light
2. Longitudinal Waves
• The direction of oscillation of a particle is the same as the direction of propagation of the wave.
• Eg. Sound waves
3. The principal of Linear Suspension
• When two or more waves are present simultaneously at the same place the resultant disturbance is the sum of of the disturbances from the individual waves
• Standing waves:
• When two periodic travelling waves of the same frequency and amplitude, moving in opposite directions meet, they interfere with each other and result in a "standing wave"
4. Condensations
Regions of higher molecular density - air pressure less than atmospheric
5. Rarefaction
Regions of lower molecular density - air pressure less than atmospheric
6. The Doppler Effect
The change in sound frequency experienced by a listener when there is a non-zero relative velocity between the source of sound and the listener
7. Amplitude
The maximum distance travelled by a particle in the wave medium, measured with respect to the undisturbed position
8. Beat Frequency
• Beats occur when there are two waves present and there is a small difference in frequency between them.
• The Beat Frequency is:
• The absolute value of the difference in frequency of the two waves |f2-f1|
9. Wavelength (λ)
The horizontal distance between two crests on the wave (or two troughs)
10. Frequency (f)
• The rate at which the wave is travelling.
• Units: s-1 or Hertz (Hz)
• 1Hz = 1s-1
11. Period (T)
• The time required for one complete "up-down" oscillation cycle.
• Units: seconds
12. Wave Equation
Y = A Sin (2 pi f t ± 2pix/λ)
13. Coulomb's Law
The force (in Newtons) between two points charges q1 and q2, separated by distance, r, and in a medium with permittivity εo can be expressed as: F= K |q1||q2|/r2
14. Electric Potential
• the electric potential V at given point is electric potential energy EPE of a small test charge qo
• situated at that point, divided by the charge itself V=EPE/qo
• Unit: Joule/Coulomb + Volt (V)
15. Electric Potential Energy (Wikipedia)
Potential energy that results from conservative Coulombs forces and is associated with the configuration of a particular set of point charges within a defined system
16. Dielectric Material
• A substance which is a poor conductor of electricity but an efficient supporter of electrostatic fields.
• The role of the dielectric is to alter the electric field line between the plates and to prevent movement of charge between the plates
17. Conventional Current
• The flow of positive charge
• (from the positive terminal to the negative terminal)
18. Alternating Current
An electric current that reverses its direction many times a second at regular intervals
19. Resistivity
A measure of the resisting power of a specified material to the flow of an electric current
20. Kirchhofs's Voltage
Around any closed-loop circuit, the sum of the potential drops equals the sum of the potential rises
 Author: McDeirdree ID: 272363 Card Set: Physics Definitions Updated: 2014-04-29 11:48:46 Tags: Physics Folders: Description: 1st year Physics; Semester 1 Show Answers: