12.5 Stationary and progressive waves Melde’s experiment A string of fixed length l and constant tension T is set in motion by ‘bowing’ a tuning fork. The above waveform occurs since an incident wave interferes with its own reflected wave causing a stationary wave. T

12.5 Stationary and progressive waves Melde’s experiment A string of fixed length l and constant tension T is set in motion by ‘bowing’ a tuning fork. The above waveform occurs since an incident wave interferes with its own reflected wave causing a stationary wave. T

12.5 Stationary and progressive waves Melde’s experiment A string of fixed length l and constant tension T is set in motion by ‘bowing’ a tuning fork. The above waveform occurs since an incident wave interferes with its own reflected wave causing a stationary wave. λ Node Anti-node T

12.5 Stationary and progressive waves Melde’s experiment A string of fixed length l and constant tension T is set in motion by ‘bowing’ a tuning fork. The above waveform occurs since an incident wave interferes with its own reflected wave causing a stationary wave. λ Node Anti-node A B C Within segment AB: particles are all in phase, have different amplitudes ( from zero at nodes to a max at antinodes) AB and BC: particles are 180^ out of phase T

Stationary waves result from the superposition of two progressive waves travelling in opposite directions with the same Amplitude, Frequency and Speed Condition for the simplest stationary wave (fundamental mode): The distance between adjacent nodes = / 2 λ Because there is zero amplitude at nodes and the nodes and antinodes are at fixed positions, no energy is transferred in a freely vibrating stationary wave

An incident wave interferes with its own reflected wave causing a stationary wave with micro waves. * No signal is produced at nodes Q Where will total cancellation occur?