PH02

PH02

1. Waves

   • Terminology
     • Amplitude - the maximum displacement from the equilibrium position. This is the volume of sound.
     • Frequency - number of oscillation per second. This is the pitch of sound. v = fλ (v is the wave speed, f is frequency, λ is wavelength).
     • Time Period - the time taken for one oscillation.
     • Wavelength - the distance between adjacent crests, more generally being the distance between two places where the oscillations are in phase.
     • Wavefront - the leading edge of one pulse.
     • Coherence - waves from the same source, have a constant phase relationship and of the same frequency or wavelength.
     • Path difference - the difference between the distances travelled from their sources by two waves meeting at a point.
     • Superposition - the combination of two or more waves.
     • Phase
       • Phase - the stage an oscillation has reached in its cycle.
       • In Phase - two oscillations exactly in step.
       • Phase Difference - when two oscillations reach their peaks and troughs at different times they have this between them.
       • Anti-Phase - when one oscillation has a peak and the other has a trough at the same point in time (they have a difference of π radians).
   • Electromagnetic Spectrum
     • Electromagnetic Spectrum
   • Wave Equation
     • v = fλ
   • Types of Waves
     • Longitudinal
       • Longitudinal Waves - oscillations along the direction of wave propagation.
       • Sound waves.
     • Transverse
       • Transverse Waves - oscillations at right angles to the direction of wave propagation.
     • Standing
       • Waves are reflected back and forth.
       • Nodes - point of no movement.
       • Anti-Nodes - point of movement.
   • Refraction
     • 1μ2 = sin i/sin r = v1/v2
   • Polarisation
     • Plane polarised light - light that travels in one plane.

2. DC Electricity

   • Current
     • Current is the rate of flow of electrons.
     • I = ∆Q /∆t
     • V = W/Q
     • I = nqvA
   • Power
     • P = VI
       • P=I^2R
       • P=V^2/R
       • W = VIt
     • Power - rate of work.
   • Resistance
     • R = V/I
     • Ohms Law
       • I α V
     • R = ρl/A

3. Nature of Light

   • Wave-Particle Duality
     • Wave
       • Light can be polarised.
       • Has a frequency.
     • Particle
       • A light particle is a photon.
       • Absorption of a photon can result in the emission of a photoelectron.
       • Threshold frequency - the lowest frequency of electromagnetic radiation that will result in the emission of photoelectrons.
         • hf = φ + ½ mv^2(max)
       • Electronvolt (Ev) - a unit of energy equal to the work done on an electron in accelerating it through a potential difference of one volt.
     • The two models are joined with the equation E=hf.
   • Atomic Line Spectra
     • Atomic Line Spectra
   • Radiation Flux
     • Power per unit area.