When the displacement of a particle is maximum above from its mean position, the particle is said to be at the crest of the wave and when the displacement of a particle is maximum below the mean position, the particle is said to be at the trough. The transverse wave travels in the form of trough and crest.
TheLongitudinal wave travels in the form of compression and rarefaction. In compression, particles of medium get compressed and in rarefaction density is less than normal density. In another way, the region where the medium is compressed is known as a compression and the region where the medium is spread out is known as a rarefaction.
One crest and one trough constitute one complete wave in a transverse wave. One compression and one rarefaction constitute one complete wave in a longitudinal wave.
The maximum displacement of a particle from its mean position in a wave is called amplitude of that wave. Its SI unit is ‘m’.
The number of complete waves, set up in a medium in one second is called frequency of the wave. Its SI unit is hertz (Hz).
The time taken by wave to complete one cycle or a complete wave is called time period. Its unit is second.
The distance between two consecutive troughs or crests in a transverse wave or the distance between two consecutive compressions or rarefactions in a longitudinal wave is called wavelength. Its SI unit is meter (m).
The velocity with which wave propagates in a medium is called wave velocity. Its SI unit is m/s.
The formula showing the relation between v, f and λ is called wave equation. The product of frequency and wavelength is equal to wave velocity.
Wave velocity (v) = frequency (f) × wavelength (λ)
The number of complete waves, set up in a medium in one second is called frequency of the wave. Its SI unit is hertz (Hz). According to the definition of frequency,
f vibrations are completed in one second.
Or, 1 vibrations is completed in \(\frac{1}{f}\) second.
But, time to complete one vibrationis its time period (T)
\(\therefore\) T = \(\frac{1}{f}\)
time period = \(\frac{1}{frequency}\) |
The regions in medium where the density of particles of a medium is less are called rarefaction.
One crest and one trough in transverse wave and one compression and one rarefaction in longitudinal wave is called a complete wave.
The number of waves (or cycles) produced by the sources of sound in one second is frequency of sound. It is denoted by f or µ and unit is cycle/sec (hertz).
The distance between two consecutive troughs or crests in a transverse wave or the distance between two consecutive compressions or rarefactions in longitudinal waves is called wavelength. It is denoted by λ and its SI unit is meter (m).
The maximum displacement of a particle from its mean position is called amplitude. It is denoted by 'a'.
The relationship between wavelength (λ) , frequency (f) and velocity of wave (v) is called wave equation. The wave equation is defined as the product of frequency and wavelength and is numerically equal to the wave velocity.
i.e. Wave velocity (V) = Wavelength (λ) x Frequency (f)
V = λ x f
The frequency of boy's voice is least (i.e. 6.5 KHz) than that of girl's (i.e. 8.5KHz). We know that, for the same medium when the speed is constant the wavelength varies inversely with frequency (i.e. λ ∝ ). So, as the frequency increases, the wavelength decreases. Due to this reason, the wavelength of girl's voice is shorter than that of boys.
The sound wave with high amplitude has more intensity and carries more energy than that of the sound with low amplitude. So, such wave is transmitted to a longer distance.
The process of bending of sound wave while passing from one medium to another is called rarefaction of sound. It follows all the rules of refraction of light.
Solution:
Given,
Speed of sound (v) = 350m/s
Wavelength (λ) = 35m
Frequency of sound (f) = ?
We know,
v = λ x f
or, f =
or, f =
∴Frequency = 10 Hz
Solution:
Here,
Speed of sound (v) = 340m/s
Wavelength (λ) = 2.4cm = 0.024m
Frequency of sound (f) = ?
We know,
v = λ x f
or, f =
or, f =
Solution:
Here,
Speed of sound (v) = 332m/s
Wavelength (λ) = ?
Frequency of sound (f) = 20Hz
We know,
v = λ x f
or, λ =
or, λ =
Solution:
Here,
Speed of sound (v) = ?
Wavelength (λ) = 0.012m
Frequency of sound (f) = 20KHz = 20 x 1000 = 20000Hz
We know,
v = λ x f
= 20000 x 0.012
= 240m/s
Hence, the speed of the sound is 240 m/s.
Solution:
Here,
Speed of sound (v) = 340m/s
Shortest Wavelength (λ) = ?
Highest Frequency of sound (f) = 20KHz = 20 x 1000 = 20000Hz
We know,
v = λ x f
or, λ =
or, λ =
∴ λ = 0.017m
Hence, the shortest wavelength is 0.017m
Again similarly,
We have,
Speed of sound (v) = 340m/s
Longest Wavelength (λ) = ?
lowest Frequency of sound (f) = 20Hz
We know,
v = λ x f
or, λ =
or, λ =
∴ λ = 17m
Hence, the longest wavelength is 17m
Solution:
Here,
Speed of radio wave (v) = 3 x 108 m/s
Wavelength (λ) = ?
Frequency of sound (f) = 103.6MHz = 103.6 x 1000000 = 103600000Hz
We know,
v = λ x f
or, λ =
or, λ =
∴Wavelength = 0.29m
Solution:
Here,
Total number of complete wave (n) = 20
Time (t) = 4s
Frequency (f) = ?
We have,
f = = 20/4 = 5 Hz
Also, the distance between two crests is 3 cm
So, wavelength (λ) = 3/100 = 0.03m
Again,
Wave speed (v) = wavelength (λ) x frequency (f)
= 0.03 x 5
= 0.15m/s
Medium | Velocity |
A | 400m/s |
B | 900m/s |
C | 700m/s |
Person | Frequency |
A | 900Hz |
B | 550Hz |
C | 400Hz |
What is a wave?
A regular disturbance of the particles of a medium which propagate without net transport of the particles
A periodic disturbance of the particles of a medium which propagate without net transport of the particles
A periodic disturbance of the particles of a sound which propagate with net transport of the particles
A periodic disturbance of the particles of a medium which polarize without net transport of the particles
Which is not true about Amplitude?
It decreases as sound moves further
The greater the displacement the greater is amplitude
It increases towards the direction of wind
If amplitude is doubled , the intensity will also be doubled
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avisek paswan
during thundering,the sound of thunder is herd later than lightening,why?
Mar 02, 2017
1 Replies
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