TJC 11 Superposition

SUPERPOSITION Learning Outcomes Candidates should be able to: (a)* explain and use the principle of superposition in simple applications (b)* show an understanding of experiments which demonstrate standing (stationary) waves using microwaves, stretched strings and air columns (c)* explain the formation of a standing (stationary) wave using a graphical method, and identify nodes and antinodes, differentiating between pressure and displacement nodes and antinodes for sound waves. (d)* determine the wavelength of sound using standing (stationary) waves (e) show an understanding of the terms diffraction, interference, coherence, phase difference and path difference (f) show an understanding of phenomena which demonstrate two-source interference using water waves, sound waves, light and microwaves (g) show an understanding of the conditions required for two-source interference fringes to be observed (h) recall and use the equation  = ax/D to solve problems for double-slit interference, where a is the slit separation and x is the fringe seperation (i) recall and use the equation asin = n to solve problems involving the principal maxima of a diffraction grating, where a is the slit seperation (j) describe the use of a diffraction grating to determine the wavelength of light (knowledge of the structure and use of a spectrometer are not required). (k) (a) show an understanding of phenomena which demonstrate diffraction through a single slit or aperture, or across an edge, such as the diffraction of water waves in a ripple tank with both a wide gap and a narrow gap, or the diffraction of sound waves from loudspeakers or around corners (l) recall and use the equation bsin =  to solve problems involving the positions of the first minima for diffraction through a single slit of width b (m) recall and use the Rayleigh criterion   /b for the resolving power of a single aperture, where b is the width of the aperture * Covered in Unit 10: Waves Temasek Junior College

2 1 Principle of superposition LO (a) Principle of superposition states that when two or more waves of the same kind meet at a point, the resultant displacement of the waves at any point is the vector sum of the displacement due to each wave acting independently. 1.1 Important terms LO (e) (a) Phase difference Phase difference is an angular measure of the fraction of a cycle two particles in a wave or two waves are out of step. • When the phase difference between two waves is zero, or an integer multiple of a cycle, the waves are said to be in phase. • When the phase difference between two waves is an odd integer multiple of half cycle, the waves are said to be anti-phase. (b) Coherence Two sources are said to be coherent if waves from each source have a constant phase difference between them (and therefore they mus