The amplitude of a progressive wave is A and angular frequency is ω then energy density of the wave is (ρ is density of medium)

Question

Question

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Official Sr. Teacher Gr II NON-TSP Science (Held on : 1 Nov 2018)

Answer 1

CONCEPT:

Standing Waves or Stationary Waves: When two sets of progressive wave trains of the same type (both longitudinal or both transverse) having the same amplitude and same time period/frequency/wavelength travelling with the same speed along the same straight line in opposite directions superimpose, a new set of waves are formed. These are called stationary waves or standing waves.
- A stationary wave is formed when a wave train is reflected at a boundary. The incident and reflected waves then interfere to produce a stationary wave.

EXPLANATION:

Where A = amplitude of a progressive wave, ω = angular frequency, and ρ = density of the medium

IMPORTANT POINT:

	Progressive wave	Stationary wave
Energy and Momentum	no net transfer in energy and momentum	both move with speed c=f × λ
Frequency	All particles oscillate at the frequency except node	all particles move with the same frequency
Amplitude	it varies from zero at nodes to maximum at the antinode	it is the same for all particles
Phase Difference	all particles between nodes are at the same phase difference	any two particles have a phase difference equal to where d is the distance between two particle