Waves are used to transfer energy from one point to another without transferring the matter* r___ Waves → often used to explain physical phenomena ⇒ such as light and sound.
Basic Family of waves → sinusoidal waves.
By adding simple sinusoidal waves ⇒ complex waves can be constructed.
Example in which simple waves are added to generate a complex wave occurs in a synthesizer.
synthesizer ⇒ sound waves ⇒ are added in chosen proportions to create a new sound.
Sinusoidal wave can also be combined to cancel each other out, such like in NCH
Example of Waves
Water Waves
Waves ⇒ can be produced in water using ripple tank and a wave generator. → water waves or water ripples are not equally spaced. for systemic studies, regular waves are needed. ⇒ regular waves are produced by a wave generator electrically powered device has a dipper driven by a motor.
Waves on a Rope
Waves can also be created using a rope.
one end is fixed to wall and other end is moved repeatedly and regularly in a direction that is perpendicular to the rope
Direction in which wave shape (or wave profile) moves is the direction of the wave.
⇒ waves direction here is towards the fixed end (moves towards the right).
within each wave ⇒ particles motion is perpendicular to the waves direction.
hence, rope is the medium through which the wave moves.
- wave generator is used to create regular waves
- when the wave generator is turned on, left side of the rope moves upwards. segment A is pulled up, and this in turn pulls segment B up
- ups and down motion at A is passed along the rope. motion that is being transferred from 1 segment to its adjacent segment tells us that kinetic energy is transferred along the rope.
Segments A. B and all subsequent segments do not move along the rope. there is no transfer of matter along the rope. For any segment n the rope ⇒ motion is described as cyclical or periodic because after moving up or down, it returns to original position.
Definition
A wave is a disturbance that propagates through space, transferring energy with it but not matter #PhysicsDefinitions
Waves on a Spring
Spring with a fixed end can be stretched on the floor.
Besides moving the free end up and down like the wave on the rope ⇒ we can push and pull the free end of the spring rapidly ⇒ to create the waves.
waves travel along the spring and move towards the fixed end.
⇒ direction moved by the waves is parallel to the direction of the hand motion.
⇒ focus on single segment of spring
example its A ⇒ it is in a cyclical or periodic motion.
motion is transferred to the adjacent segments B, then C and towards the fixed end.
while the waves in the rope and the spring do not have same appearance ⇒ there are similarities between the waves.
Water Waves in a Ripple Tank
Ripple tanks is set up to demonstrate basic properties of water waves. ⇒ shallow glass tank of water is placed below a wave generator connected to a dipper when dipper touches the water surface ⇒ circular waves are produced. imaginary line that joins all adjacent points on the wave are in phase ⇒ such as the crests ⇒ is called a Wavefront
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| wave generator is mounted with its vibrating rod touching the water surface. When the dipper moves up and down, a series of circular ripples are generated (circular waves) | Long flat strip is mounted to the wave generator. When the dipper moves up and down ⇒ series of straight ripples are generated. (plane waves) |
| From examples of waves on a rope, spring and ripple tank ⇒ we can observe that motion of any selected point in a wave is periodic and repetitive. | |
| this motion is known as vibration or *Oscillation |
How can we Describe Characteristics of Waves
How can we Describe Characteristics of Waves
Wavefronts
speed of waves can also be deduced by observing Wavefronts
Wavefront ⇒ is an imaginary line joining all adjacent points that are in phase.
from the ripples produced in the ripple tank ⇒ crests and troughs can be identified.
each continuous circle of a crest or trough forms a Wavefront.
by considering particular point x on a crest and measuring how fast it travels away from the source ⇒ we can find the speed of the wave.
