Answer
64.8k+ views
Hint: Waves can be of two types longitudinal and transverse. In transverse waves, the particles vibrate perpendicular to the direction of propagation of the wave. If we take the velocity of the wave along the x axis then the displacement of the particles will be along y axis. In longitudinal waves, the particles vibrate along the direction of the propagation of the wave.
Formula Used:
1. Wave number: $k = \dfrac{{2\pi }}{\lambda }$ ……(1)
Where,
$\lambda $is the wavelength of the wave
2. Velocity of the wave: $v = \lambda \upsilon $ ……(2)
Where,
$\upsilon $ is the frequency of the wave.
3. Angular frequency: $\omega = 2\pi \upsilon $ ……(3)
4. Equation of the wave travelling in positive x direction:
$y(x,t) = A\sin (kx - \omega t + \phi )$ ……(4)
Where,
$y(x,t)$ is the displacement along y direction when the wave is at x point and at time t
$\phi $ is the phase angle
Diagram:
![](https://www.vedantu.com/question-sets/7fcc61b6-9938-4a37-ad30-1f0309d494097994270861078170514.png)
Complete step by step answer:
Given:
1. Amplitude of the wave A = 10cm
2. Wavelength of the wave $\lambda = 200cm$
3. Speed of the wave v = 100cm/s
To find: The equation of the wave in the C.G.S system.
Step 1:
Calculate k using to eq. (1):
$
\Rightarrow k = \dfrac{{2\pi }}{{200}} \\
\Rightarrow k = 0.01\pi c{m^{ - 1}} \\
$
Rearrange the terms in eq (2) to find $\upsilon $:
$\upsilon = \dfrac{v}{\lambda }$ ……(5)
Step 2:
Find frequency using eq (5):
$
\Rightarrow \upsilon = \dfrac{{100}}{{200}} \\
\Rightarrow \upsilon = 0.5Hz \\
$
Find angular frequency using eq (3):
$
\omega = 2\pi (0.5) \\
\omega = \pi Hz \\
$
Step 3:
Phase angle determines how much the 1st particle is initially displaced when t=0. When t=0, the 1st particle of the string is at origin. This means the 1st particle(x=0) is at displacement y=0 for t=0. Hence, the phase angle $\phi $ is 0.
If the point at x=0 is moving down in a negative y direction, it means that the wave has moved forward in x direction (left to right). So, it is a wave travelling in +x direction. Use eq (4) to find the equation:
$
\Rightarrow y(x,t) = 10\sin (0.01\pi x - \pi t + 0) \\
\Rightarrow y(x,t) = 10\sin (0.01\pi x - \pi t) \\
$
Final Answer
The equation of the wave is (a) \[10\sin (0.01\pi x - \pi t)\] in the C.G.S system.
Note: Try to remember the general equation of a wave propagating along the x axis. In this equation x and t are variables, the rest of the unknown quantities can be found using their definitions. For example, phase angle is the angle by which the origin of the wave has displaced with respect to the origin of the sin wave.
Formula Used:
1. Wave number: $k = \dfrac{{2\pi }}{\lambda }$ ……(1)
Where,
$\lambda $is the wavelength of the wave
2. Velocity of the wave: $v = \lambda \upsilon $ ……(2)
Where,
$\upsilon $ is the frequency of the wave.
3. Angular frequency: $\omega = 2\pi \upsilon $ ……(3)
4. Equation of the wave travelling in positive x direction:
$y(x,t) = A\sin (kx - \omega t + \phi )$ ……(4)
Where,
$y(x,t)$ is the displacement along y direction when the wave is at x point and at time t
$\phi $ is the phase angle
Diagram:
![](https://www.vedantu.com/question-sets/7fcc61b6-9938-4a37-ad30-1f0309d494097994270861078170514.png)
Complete step by step answer:
Given:
1. Amplitude of the wave A = 10cm
2. Wavelength of the wave $\lambda = 200cm$
3. Speed of the wave v = 100cm/s
To find: The equation of the wave in the C.G.S system.
Step 1:
Calculate k using to eq. (1):
$
\Rightarrow k = \dfrac{{2\pi }}{{200}} \\
\Rightarrow k = 0.01\pi c{m^{ - 1}} \\
$
Rearrange the terms in eq (2) to find $\upsilon $:
$\upsilon = \dfrac{v}{\lambda }$ ……(5)
Step 2:
Find frequency using eq (5):
$
\Rightarrow \upsilon = \dfrac{{100}}{{200}} \\
\Rightarrow \upsilon = 0.5Hz \\
$
Find angular frequency using eq (3):
$
\omega = 2\pi (0.5) \\
\omega = \pi Hz \\
$
Step 3:
Phase angle determines how much the 1st particle is initially displaced when t=0. When t=0, the 1st particle of the string is at origin. This means the 1st particle(x=0) is at displacement y=0 for t=0. Hence, the phase angle $\phi $ is 0.
If the point at x=0 is moving down in a negative y direction, it means that the wave has moved forward in x direction (left to right). So, it is a wave travelling in +x direction. Use eq (4) to find the equation:
$
\Rightarrow y(x,t) = 10\sin (0.01\pi x - \pi t + 0) \\
\Rightarrow y(x,t) = 10\sin (0.01\pi x - \pi t) \\
$
Final Answer
The equation of the wave is (a) \[10\sin (0.01\pi x - \pi t)\] in the C.G.S system.
Note: Try to remember the general equation of a wave propagating along the x axis. In this equation x and t are variables, the rest of the unknown quantities can be found using their definitions. For example, phase angle is the angle by which the origin of the wave has displaced with respect to the origin of the sin wave.
Recently Updated Pages
Write a composition in approximately 450 500 words class 10 english JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Arrange the sentences P Q R between S1 and S5 such class 10 english JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What is the common property of the oxides CONO and class 10 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What happens when dilute hydrochloric acid is added class 10 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
If four points A63B 35C4 2 and Dx3x are given in such class 10 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
The area of square inscribed in a circle of diameter class 10 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Other Pages
Excluding stoppages the speed of a bus is 54 kmph and class 11 maths JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
In the ground state an element has 13 electrons in class 11 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Electric field due to uniformly charged sphere class 12 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
A boat takes 2 hours to go 8 km and come back to a class 11 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
According to classical free electron theory A There class 11 physics JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Differentiate between homogeneous and heterogeneous class 12 chemistry JEE_Main
![arrow-right](/cdn/images/seo-templates/arrow-right.png)