Wave Motion and Periodic Motion

• Waves transfer energy without transferring matter.

What is a Wave?

• A wave is a disturbance that transfers energy from one place to another through vibrations or oscillations.
• Waves are made up of vibrations and oscillations.

Periodic Motion

• Periodic motion is motion repeated at regular intervals.
• The swing of a pendulum is periodic.
• A pendulum moves from point A to B, and back to A at regular intervals.
• When a pendulum moves from A to B and back to A, it completes a cycle.

Wave Motion

• A wave can be transferred from one end to another.
• Up and down motion causes a hump (wave), which moves towards the fixed end (wall).
• Movement from the hand transfers energy to the rope.
• A rope wave is a wave that travels within a rope.
• The rope wave moves from the hand to the wall.
• As a wave moves through a rope, from left to right, the rope particles (P and Q) move up and down about their original position.
• Eventually, kinetic energy is transferred from the hand to the wall.
• The source of a wave is a vibration or an oscillation.
• Waves only transfer energy from one point to another.
• Waves transfer energy without transferring matter.

Types of Waves

• Moving a spring creates motion.
• The individual spring coils move perpendicular to the direction of the wave.
• There are two types of waves, transverse and longitudinal.

Transverse Waves

• The coils move up and down, while the wave moves from left to right.
• The movement of the coils is perpendicular to the wave motion.
• Transverse waves travel perpendicular to the direction of wave.
• Examples of transverse waves are light (electromagnetic waves), water waves, and rope waves.

Longitudinal Waves

• The coils move to the left and right, while the wave moves from left to right.
• The movement of the coils is parallel to the wave motion.
• Longitudinal waves travel parallel to the direction of the wave.
• An example of longitudinal waves is sound.

Waves in a Ripple Tank

• Energy from the dipper is transferred to the water.
• Forms a water wave (a water ripple).
• The water wave moves away from the dipper.
• Kinetic energy is transferred from the dipper to the edges of the ripple tank.
• Water particles move up and down and oscillate about their original position.
• One wavefront to another wavefront equals one wavelength.

Wavefront

• A wavefront is a line on a wave that joins all adjacent points in phase.