Physics

Wave Motion

489 Questions

Wave motion questions cover the principles of traveling and stationary waves, including their equations and intensities. The topics explore interference patterns, phase differences, and electromagnetic radiation speeds. Mastery of these concepts is vital for physics sections in engineering and civil services examinations.

Wave interferenceStanding wavesPhase differenceElectromagnetic radiationWave equations

Wave Motion Questions

Multiple choice

How are Wavelength and Amplitude Related?

  1. As you Increase the Amplitude, the Wavelength will Decrease

  2. As you Increase the Amplitude, the Wavelength will Increase

  3. As you Decrease the Amplitude, the Wavelength will Increase

  4. They are NOT Related
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics behaviour of perfect gas and kinetic theory of gases degree of freedom: law of equipartition of energy law of equipartition of energy law of equipartition of energy and mean free path

The speed of a longitudinal wave in a mixture containing 4 moles of He and 1 mole of Ne at 300 K will be

  1. 930 m/s

  2. 541 m/s

  3. 498 m/s

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The mixture contains $n _1=4\ mol$ of $He$ and $n _2=4\ mole$ of $Ne$ act. $T=300\ K$.
Forth $He$ and $Ne$ are monoatomic, so we take $r$ mix $=5/3\quad \left [r=\dfrac {cp}{cv}\right]$ 
$M'=\dfrac {M _1n _1+M _2n _2}{n _1+n _2}$
$=\dfrac {4\times 4+20\times 1}{4+1}=\dfrac {24}{5}=4.8\ g/mol$
$=4.8\times 10^{-3}\ kg/mol$
$\therefore \ $ Speed of sound through mixture
$v=\sqrt {\dfrac {vRT}{M'}}=\sqrt {\dfrac {5}{3}\times \dfrac {8.3\times 300}{4.8\times 10^{-3}}}\sim 929.83\ m/s$


Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

A plane electromagnetic wave of frequency $40 MHz$ travels in free space in the X-direction. At some point and at some instant, the electric field $\vec{E}$ has its maximum value of $750N/C$ in Y-direction. The wavelength of the wave is-

  1. 3.5 m

  2. 5.5 m

  3. 7.5 m

  4. 9.5 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The wavelength of an electromagnetic wave is calculated using the relation lambda = c / f, where c is the speed of light in vacuum (3 times 10^8 m/s) and f is the frequency (40 MHz or 40 times 10^6 Hz). Dividing 3 times 10^8 by 40 times 10^6 yields 7.5 meters. The electric field amplitude is extra information not needed to find the wavelength.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

If the distance that a radio wave can travel in the time of one complete cycle is $10$ metres, then the frequency of the radio wave in cycles per second is?

  1. $3\times 10^9$Hz
  2. $3\times 10^6$Hz
  3. $3\times 10^8$Hz
  4. $3\times 10^7$Hz
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The speed of a wave is given by v = frequency x wavelength. Here, the distance traveled in one cycle is the wavelength (lambda = 10 m). Using v = 3 x 10^8 m/s, we get frequency = v / lambda = (3 x 10^8) / 10 = 3 x 10^7 Hz.

Multiple choice

Which method is used to solve the wave equation?

  1. Method of Characteristics

  2. Separation of Variables

  3. Laplace Transform

  4. Fourier Series
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Separation of Variables is a powerful technique for solving the wave equation. It involves finding solutions that are products of functions, each depending on a single independent variable.

Multiple choice

The principle of superposition states that the total displacement of a point in a medium due to multiple waves is the:

  1. Sum of the displacements due to each wave

  2. Difference of the displacements due to each wave

  3. Product of the displacements due to each wave
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of superposition states that when multiple waves overlap in a medium, the resulting displacement at any point is the sum of the displacements that would be caused by each wave individually. This principle is fundamental to understanding wave phenomena such as interference and diffraction.

Multiple choice

What is the term used to describe the lowest point of a wave?

  1. Crest

  2. Trough

  3. Wavelength

  4. Amplitude
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The trough is the lowest point of a wave, where the water is displaced vertically downward from its equilibrium position.

Multiple choice

What is the distance between two consecutive crests or troughs of a wave?

  1. Crest

  2. Trough

  3. Wavelength

  4. Amplitude
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The wavelength is the distance between two consecutive crests or troughs of a wave. It is a measure of the horizontal extent of a wave.

Multiple choice

What is the vertical distance between the crest and the trough of a wave?

  1. Crest

  2. Trough

  3. Wavelength

  4. Amplitude
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The amplitude is the vertical distance between the crest and the trough of a wave. It is a measure of the wave's strength or intensity.

Multiple choice

What is the speed at which a wave travels?

  1. Wave velocity

  2. Wave frequency

  3. Wave period

  4. Wave amplitude
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Wave velocity is the speed at which a wave travels. It is determined by the properties of the medium through which the wave is propagating.

Multiple choice

What is the relationship between wave velocity, wavelength, and frequency?

  1. v = λf

  2. v = λ/f

  3. v = f/λ

  4. v = λ^2f
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The relationship between wave velocity, wavelength, and frequency is given by the equation v = λf, where v is the wave velocity, λ is the wavelength, and f is the frequency.

Multiple choice

A vibrating string is described by the wave equation (\frac{\partial^2 u}{\partial t^2} = c^2\frac{\partial^2 u}{\partial x^2}), where (c) is the wave speed. What is the general solution to this equation?

  1. \(u(x, t) = f(x - ct) + g(x + ct)\)
  2. \(u(x, t) = f(x - ct) - g(x + ct)\)
  3. \(u(x, t) = f(x + ct) + g(x - ct)\)
  4. \(u(x, t) = f(x + ct) - g(x - ct)\)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general solution to the wave equation is given by (u(x, t) = f(x - ct) + g(x + ct)), where (f) and (g) are arbitrary functions.

Multiple choice

A vibrating string is described by the wave equation (\frac{\partial^2 u}{\partial t^2} = c^2\frac{\partial^2 u}{\partial x^2}), where (c) is the wave speed. What is the general solution to this equation?

  1. \(u(x, t) = f(x - ct) + g(x + ct)\)
  2. \(u(x, t) = f(x - ct) - g(x + ct)\)
  3. \(u(x, t) = f(x + ct) + g(x - ct)\)
  4. \(u(x, t) = f(x + ct) - g(x - ct)\)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general solution to the wave equation is given by (u(x, t) = f(x - ct) + g(x + ct)), where (f) and (g) are arbitrary functions.

Multiple choice

What is the Fourier transform?

  1. A mathematical operation that converts a function of time or space into a function of frequency.

  2. A mathematical operation that converts a function of time or space into a function of amplitude.

  3. A mathematical operation that converts a function of time or space into a function of phase.

  4. A mathematical operation that converts a function of time or space into a function of wavelength.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Fourier transform is a mathematical operation that converts a function of time or space into a function of frequency, allowing for the analysis of the frequency components of a signal.