# Wave & Optics - Objectives Content

• Progressive waves

• Transverse waves

• Longitudinal waves

• Polarisation

• Interference

• Standing waves

• Refraction of light

• Total internal reflection

Learning Outcomes

• Oscillation of the particles of the medium; definitions of:
• amplitude
• frequency
• wavelength
• speed
• phase
• phase difference (in radians, degrees or fractions of a cycle)
• c = fλ
• f = 1/T
• Characteristics and examples of longitudinal and transverse waves, including sound, electromagnetic waves and waves on a string.
• the direction of displacement of particles/fields relative to the direction of energy propagation.
• Electromagnetic waves all travel at the same speed in a vacuum.
• Polarisation as evidence for the nature of transverse waves; applications e.g. Polaroid sunglasses, aerial alignment for transmitter and receiver.
• The formation of stationary waves by two waves of the same frequency travelling in opposite directions; no mathematical treatment required but graphical explanation is expected.
• Simple graphical representation of stationary waves, nodes and antinodes on strings.
• f = 1/2L x (√ T/μ) for the first harmonic (fundamental)
• Stationary waves formed on a string and those produced with microwaves and sound waves.
• The terms fundamental and overtone will not be used.
• Refractive index of a substance s , ns = c/cs; Candidates are not expected to recall methods for determining refractive indices
• The refractive index of air being approximately 1
• Snell's Law of refraction for a boundary between two different substances of refractive indices n1 and n2 in the form:
n1sin θ1 = n2sin θ2

• Total internal reflection including calculations of the critical angle θc at a boundary between a substance of refractive index n1 and a substance of lesser refractive index n2 or air:
sin θc = n2/ n1
• Simple treatment of fibre optics including function of the cladding with lower refractive index around central core limited to step index only; application to communications.
• Material and modal dispersion
• the principles and consequences of pulse broadening and absorption
• REQUIRED PRACTICAL - investigation into the variation of the frequency of stationary waves on a string with length, tension and mass per unit length of the string. 