Sound and light
Summary of lesson (1)
The vibrational motion and the wave motion
Sound:
It is an external factor that affects the ear causing the sense of hearing.
The vibrational motion
- It is the motion produced by the vibrating body at the two sides of its original position.
Examples of the vibrational motion
a- The motion of the simple pendulum.
b- Spiral wire.
c- The tuning fork.
The complete vibration
- It is the motion of the vibrating body through an interval of time as it passes by a fixed point on its path two successive times in one direction with the same velocity.
The amplitude:
- It is the maximum displacement that is done by the vibrated body away from its original position.
- The complete vibration includes four displacements each of them is called amplitude.
The frequency "":
It is the number of the complete vibrations that is made by the vibrating body in one second.
Hertz: "Hz"
(complete vibration / second) cycle / second.
- It the complete vibration produced in one second.
- Is the measuring unit of frequency.
The periodic time "t"
It is the time taken by the vibrating body to make one complete vibration.
The wave motion:
The total movement of the patricles of the medium in a certain moment with a definite direction.
The wave:
It is a distribance in the medium that propagates in a definite direction and speed and it transfers the energy in its spread direction.
They are the waves that need a medium to propagrate
Transverse waves:
- They are mechanical waves in which the particles of the medium vibrate perpendicular to the direction of the wave propagation.
- It consists of crests and troughs.
Crest:
It is the maximum displacement of the particles of the medium upwards.
Trough:
It is the maximum displacment of the particles of the medium downwards.
The wave length of a transverse wave:
It is the distance between two successive crests or troughs.
Longitudinal waves:
- They are mechanical waves in which the particles of the medium vibrate in the same direction of the propagation of a wave without movement.
- It consists of compressions and rarefactions.
Compression:
It is the region where particles of the medium become very close to each other.
Rarefaction:
It is the region where the particles of the medium are far apart from each other.
The wave length of the longitudinal wave:
It is the distance between the centers of two successive compressions or the centers of two successive rarefactions.
Electromagnetic waves:
They are the waves that spread in space and do not need a medium to propagate.
The relationship between the frequency and the wave length in the wave motion:
The wave propagation law:
Wave velocity = frequency x wave len
gthSummary of lesson (1)
The vibrational motion and the wave motion
Sound:
It is an external factor that affects the ear causing the sense of hearing.
The vibrational motion
- It is the motion produced by the vibrating body at the two sides of its original position.
Examples of the vibrational motion
a- The motion of the simple pendulum.
b- Spiral wire.
c- The tuning fork.
The complete vibration
- It is the motion of the vibrating body through an interval of time as it passes by a fixed point on its path two successive times in one direction with the same velocity.
The amplitude:
- It is the maximum displacement that is done by the vibrated body away from its original position.
- The complete vibration includes four displacements each of them is called amplitude.
The frequency "":
It is the number of the complete vibrations that is made by the vibrating body in one second.
Hertz: "Hz"
(complete vibration / second) cycle / second.
- It the complete vibration produced in one second.
- Is the measuring unit of frequency.
The periodic time "t"
It is the time taken by the vibrating body to make one complete vibration.
The wave motion:
The total movement of the patricles of the medium in a certain moment with a definite direction.
The wave:
It is a distribance in the medium that propagates in a definite direction and speed and it transfers the energy in its spread direction.
They are the waves that need a medium to propagrate
Transverse waves:
- They are mechanical waves in which the particles of the medium vibrate perpendicular to the direction of the wave propagation.
- It consists of crests and troughs.
Crest:
It is the maximum displacement of the particles of the medium upwards.
Trough:
It is the maximum displacment of the particles of the medium downwards.
The wave length of a transverse wave:
It is the distance between two successive crests or troughs.
Longitudinal waves:
- They are mechanical waves in which the particles of the medium vibrate in the same direction of the propagation of a wave without movement.
- It consists of compressions and rarefactions.
Compression:
It is the region where particles of the medium become very close to each other.
Rarefaction:
It is the region where the particles of the medium are far apart from each other.
The wave length of the longitudinal wave:
It is the distance between the centers of two successive compressions or the centers of two successive rarefactions.
Electromagnetic waves:
They are the waves that spread in space and do not need a medium to propagate.
The relationship between the frequency and the wave length in the wave motion:
The wave propagation law:
Wave velocity = frequency x wave len
