Physics Definitions

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Physics Definitions
2014-04-29 07:48:46

1st year Physics; Semester 1
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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