EJC Physics H212b Superposition 2023 1. Notes (full)

9749(202 3) H2 Physics H212 Superposition – Notes Page 1 of 15 H2 Topic 12b – Superposition A Water Spouting Bowl is a dramatic demonstration of standing waves. When damp hands run over the handles under the right conditions, resonance occurs and standing waves form around the circular bronze bowl, res ulting in water ejecting at antinodes around the rim. Content (H211 Waves) • Determination of frequency and wavelength of sound waves Learning Objectives: Candidates should be able to: (k) determine the wavelength of sound using stationary waves Content (H212 Superposition) • Stationary waves Learning Outcomes Candidates should be able to: (c) show an understanding of experiments which demonstrate stationary waves using microwaves, stretch strings and air columns (d) explain the formation of a stationary wave using a graphical method, and identify nodes and antinodes 12.4 Stationary Waves In H211 Waves , we learnt that a progressive wave transports energy. Here, we shall see how the superposition of two waves can cause interference such that energy is localised (confined within a region) despite wave motion. The waves formed are called stationary waves or standing waves. The wave is stationary because the wave profile does not propagate although the particles still oscillate. Because the wave profile does not move, energy is not transmitted along the wave. wave 1 wave 2 resultant The resulting standing wave has a wave profile that visually moves up and down. We can also think of it as two waves transporting energy in opposite directions, so “net -net” the energy no longer is transported and hence is “stationary”.

9749(202 3) H2 Physics H212 Superposition – Notes Page 2 of 15 12.4.1 Region of Overlap For the phenomena that we have seen earlier in H212a, we apply the Principle of Superposition at a particular location on the screen. For standing waves, we apply the principle over the entire length over which two waves meet and overlap. 12.4.2 Formation of Stationary Waves When asked to explain the formation of stationary waves in a particular set up, with the necessary features mentioned above in mind, be sure to describe: • how 2 progressive waves of the same type are generated such that they are the same amplitude, frequency, wavelength and speed • how the 2 waves are travelling in opposite directions towards each other • where the 2 waves meet and overlap source 1 source 2 bright fringe waves superpose here at a spot on the screen wave 1 wave 2 resultant waves superpose across whole length A stationary wave is formed when two waves of the same type, same amplitude, same frequency, wavelength and speed, travelling in opposite directions towards each other, meet and overlap to superpose across a length. For A-Level H2 Physics, standing waves are almost only 1D such as on a string or along a column. In real life, t