Wave Equation and Interference Principles

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Questions and Answers

What happens to the amplitude of a new wave resulting from the superposition of two waves of the same frequency?

It remains constant regardless of the original amplitudes.
It becomes less than the lowest original amplitude.
It can be greater than both original amplitudes. (correct)
It becomes the average of the two amplitudes.

Which condition is necessary for the coherent superposition of waves?

The waves must be of different frequencies.
The waves must travel in opposite directions.
The waves must have the same amplitude.
The waves must have a fixed phase relationship. (correct)

What defines the speed at which maximal constructive interference propagates through a medium?

Speed of individual runners
Phase velocity
Velocity of low frequency waves
Group velocity (correct)

What phenomenon occurs when two sound waves of different frequencies interfere?

Beat phenomenon. (B) Signup and view all the answers

What does the beat frequency represent in wave interference?

The difference between the two frequencies. (A) Signup and view all the answers

In a non-dispersive medium, how is the beat frequency derived?

From the difference in frequencies of two waves (A) Signup and view all the answers

Which type of medium is characterized by group velocity being less than phase velocity?

Normal dispersive medium (C) Signup and view all the answers

In the context of data transmission, what can the higher frequency waves be referred to as?

Carrier waves. (B) Signup and view all the answers

What is the relation between phase velocity (vp) and group velocity (vg) in a non-dispersive medium?

vg = vp (B) Signup and view all the answers

What is meant by phase and group velocity analogy in the context of running marathon runners?

Runners appear to move uniformly for a brief period. (B) Signup and view all the answers

What role does frequency modulation (fm) or amplitude modulation (am) play in wave transmission?

They help in transmitting signals effectively. (C) Signup and view all the answers

What is the primary factor that causes a group to disperse over time during a race?

Different speeds of individual runners (A) Signup and view all the answers

How does the principle of superposition apply to waves?

It allows waves to combine, resulting in either constructive or destructive interference. (B) Signup and view all the answers

What can be said about the electric fields when considering the superposition of waves?

They are all parallel to one another. (D) Signup and view all the answers

What happens to wave velocities in a medium where vg < vp?

Higher frequency waves travel slower than lower frequency waves. (C) Signup and view all the answers

What effect does moving at different frequencies have on wave velocity within a medium?

It can affect the overall velocity of the waves. (C) Signup and view all the answers

What does the principle of superposition state regarding the displacement of waves?

The resultant displacement is the vector sum of the displacements of the individual waves. (C) Signup and view all the answers

What is the formula used to determine the resultant wave when two waves overlap?

y(x, t) = y1(x, t) + y2(x, t) (A) Signup and view all the answers

In the context of waves, what phenomenon occurs when two waves interfere constructively?

The amplitude of the resultant wave increases. (B) Signup and view all the answers

What is the effect of destructive interference on wave amplitudes?

It results in a wave with reduced amplitude and can lead to complete cancellation. (A) Signup and view all the answers

What describes the 'beat phenomenon' in wave interaction?

It occurs when two waves of slightly different frequencies interfere. (D) Signup and view all the answers

What does phase velocity refer to in wave propagation?

The speed at which the wave crest moves. (D) Signup and view all the answers

What is the primary characteristic of a harmonic wave?

It has a regular periodic pattern in time and space. (B) Signup and view all the answers

What happens when two waves traveling in opposite directions overlap according to the superposition principle?

They create a standing wave pattern with nodes and antinodes. (B) Signup and view all the answers

Study Notes

Wave Equation

The wave equation describes the behavior of a wave in space and time.
The initial amplitude of a wave can be zero or a maximum depending on whether a sine or cosine function is used.
The general form for a propagating wave is given by: y(x,t) = A sin(kx - ωt + φ).
The initial phase is determined by the initial conditions.

Interaction of Propagating Waves

When two or more waves travel through the same medium, their displacements add together, resulting in a combined wave.
This principle is known as the principle of superposition.

Superposition Principle

The resultant displacement of a wave is the sum of the separate displacements of the constituent waves.
When two waves with the same frequency and amplitude overlap, they can interfere constructively or destructively.

Constructive Interference

Occurs when the waves are in phase and their amplitudes add together.

Destructive Interference

Occurs when the waves are out of phase and their amplitudes subtract from each other.

Beat Phenomenon

When two sound waves of different frequencies approach the ear, the alternating constructive and destructive interference causes the sound to be alternately soft and loud.
This wave disturbance is called 'beats'.
The beat frequency is the difference in frequency between the two waves.

Phase and Group Velocity

The phase velocity is the speed of an individual harmonic wave.
The group velocity is the speed of the overall wave packet or group of waves.
In a non-dispersive medium, the phase and group velocities are equal.
In a dispersive medium, the phase and group velocities are different because the speed of the waves depends on their frequency.
The group velocity is generally less than the phase velocity in a normal dispersive medium.
In anomalous dispersive media, the group velocity can exceed the phase velocity.
The relation between group and phase velocity is: vg = vp (1 - λ dn/n dλ).

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Description

This quiz explores the fundamentals of wave equations and the principles of wave interaction, including superposition, constructive, and destructive interference. Test your understanding of how waves behave and combine in different scenarios.