Tag: standing waves in strings

Questions Related to standing waves in strings

When we hear a sound, we can identify its source from : 

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. Amplitude of sound

  2. Intensity of sound

  3. Wavelength of sound

  4. Overtones present in the sound

Show answer
Correct Option: D
Explanation:

Answer is D.

When we hear a sound, we can identify its source from overtones present in the sound.
The fundamental is the frequency at which the entire wave vibrates. Overtones are other sinusoidal components present at frequencies above the fundamental. All of the frequency components that make up the total waveform, including the fundamental and the overtones, are called partials. Together they form the harmonic series.
Overtones which are perfect integer multiples of the fundamental are called harmonics. When an overtone is near to being harmonic, but not exact, it is sometimes called a harmonic partial, although they are often referred to simply as harmonics. Sometimes overtones are created that are not anywhere near a harmonic, and are just called partials or inharmonic overtones.

The vibrations produced by the body after it is into vibration is called ....................

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. Force Vibrations

  2. Free or Natural Vibrations

  3. Damped Vibrations

  4. None of these

Show answer
Correct Option: B

The length of a stretched string is $2 m$. The tension in it and its mass are $10 N$ and $0.80 kg$ respectively. Arrange the following steps in a sequence to find the third harmonic of transverse wave that can be created in the string.
(a) Find the linear mass density ($m$) using the formula, $m$ $\displaystyle = \dfrac{mass (M)  of \ the \  string}{length (l)  of \ the \  string}$
(b) Collect the data from the problem and find the length($l$) tenstion ($T$) and mass ($M$) of the stretched string.
(c) The fundamental frequency of a stretched vibrating string is given by $n$ $=\displaystyle \dfrac{1}{2l} \sqrt{\dfrac{T}{m}}$
(d) The frequency of $2^{nd}$ overtone or $3^{rd}$ harmonic is given by $n _2\displaystyle = \dfrac{3}{2l}\sqrt{\dfrac{T}{m}}=3n$.

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. a b c d

  2. d b c a

  3. b a c d

  4. b d c a

Show answer
Correct Option: C
Explanation:

Collect the data from the problem and find the length ($l$), tension ($T$) and mass ($M$) of the stretched string (b). 

Find the linear mass density (m) using the formula, m $= m/l$  (a).
The fundamental frequency of a stretched vibrating string is given by, n $=\displaystyle \dfrac{1}{2l} \sqrt{\dfrac{T}{m}}$ (c).
The frequency of $2^{nd}$ overtone or $3^{rd}$ harmonic is given by $n _2=\displaystyle \dfrac{3}{2l} \sqrt{\dfrac{T}{m}}=3n$ (d)

All overtones are stationary wave.

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

All overtones are not stationary waves. Only those overtones which match the frequencies of the harmonics act as stationary waves.

All harmonics in a stringed instrument are

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. Standing waves

  2. Progressive wave

  3. Electromagnetic waves

  4. Transverse waves

Show answer
Correct Option: A
Explanation:

All harmonics in a stringed instrument are stationary or standing waves

The correct option is (a)

nth overtone and (n/2) harmonic are always equal

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

$n^{th}$ overtone is always equal to (n+1) harmonic.

For example :
First overtone = second overtone 
Second overtone = third overtone 

All harmonics are possible in a string fixed at one end

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

In a string fixed at one end, only odd harmonics are allowed

A set of 3 standing waves 5, 10 and 15 Hz are to be setup on a string fixed at one end. One of these frequencies are suppressed, while passing through it. Identify them:

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. 5 Hz

  2. 10 Hz

  3. 15 Hz

  4. All the frequencies will pass through them

Show answer
Correct Option: B
Explanation:

In a string fixed at one end, only odd harmonics are allowed and even harmonics are suppressed.

Thus the 10Hz standing wave is suppressed,
The correct option is (b)

The 3rd overtone for a string fixed at one end is 

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. 3rd harmonic

  2. 5th harmonic

  3. 1st harmonic

  4. fundamental note

Show answer
Correct Option: B
Explanation:

The  third overtone is the 5th harmonic, since odd harmonics are only allowed in  a string fixed at one end

The correct option is (b)

A medium will not support an infinite number of standing waves of continuously different wavelengths

physics oscillations and waves standing waves in strings standing waves reflection of waves

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Only certain sized waves will stand on any one medium and thus a medium can be tuned to accept only certain waves or certain vibrations