WAVES
Wave motion in a
medium is due to the generated disturbance which causes the constituent
particles to repeat its to and fro motion about its mean position in equal
interval of time, and this disturbance is passed over from one end of the
medium to the other. Wave is form of energy.
Example:
Dip one end of a pencil at the edge of a tub containing water. Rapidly move the
pencil up and down vertically. The ripples spread outwards on the surface of
the water. Place some small pieces of cardboard equally spaced in the direction
of the waves, and observe the movement of pieces as the wave pass. Every piece
of cardboard moves up and down about its mean position. They are not displaced
forward from their original positions along with the water waves. The motion of
these pieces about their mean position is known as vibratory motion.
TYPES OF
WAVES
There are two
types of waves.
1. MECHANICAL WAVES: The
waves which require a medium for their propagation is known as mechanical
waves. It is further divided into two
types.
(i) Transverse waves: Transverse waves are such waves in which the particles of the medium vibrate perpendicular to the direction of propagation of the wave.
Example:
Water waves, waves produced by the string
(ii) Compressional or longitudinal
waves. Waves
in which the direction of the vibratory motion of the particles of the medium
is parallel to the direction of propagation of the wave.
Example:
Motion of a spring system, sound waves.
2. ELECTROMAGNETIC WAVES:
The waves which do not require a medium for their propagation is known as
electromagnetic waves.
Example:
Radio waves, Television waves, X-rays, etc.
WAVES ARE CARRIERS OF ENERGY.
Energy can be
transferred through matter and waves.
Experiment: Dip one end of a pencil at the edge of a tub containing water. Rapidly move the pencil up and down vertically. The ripples spread outwards on the surface of the water. Place a cork on the surface of water near the other end of the tub opposite to the pencil. When waves pass through this cork, the cork vibrates up and down perpendicular to the water surface at its place. We impart energy in moving the pencil up and down. This energy reaches the cork through water waves due to which cork vibrates.
RIPPLE TANK
Ripple tank is a simple apparatus which used to study the properties of waves
like reflection, refraction, etc.
Construction: This tank consists of a rectangular tray with glass bottom and is placed nearly half meter above the surface of table by means of four supporting legs. Waves are produced on the surface of water present in the tray by means of a vibrator. This vibrator is an oscillating electric motor which is fixed on a wooden plate. This plate is suspended by means of rubber bands and its lower end touches the water surface. On setting vibrator ON, this plate starts vibrating and straight waves are generated on the water surface.
Very Important and easy to understand. Nice written.
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