matter & Energy
A wave is a repeating disturbance or vibration that transfers or moves energy from place to place.
- Waves are created when a source of energy (force) causes a vibration.
- A vibration is a repeated back-and-forth or up-and-down motion.
- Waves carry energy through empty space or through a medium without transporting matter.
- While all waves can transmit energy through a medium, certain waves can also transmit energy through empty space.
- A medium is a material through which waves can travel. It can be a solid, liquid, or gas.
- When waves travel through a medium, the particles of the medium are not carried along with the wave.
- When there is no medium, certain waves (electromagnetic) can travel through empty space
- Mechanical waves require the particles of the medium to vibrate in order for energy to be transferred.
- For example, water waves, earthquake/seismic waves, sound waves, and the waves that travel down a rope or spring are also mechanical waves.
- Sound waves, as with all mechanical waves, cannot be transferred or transmitted through empty space (vacuum).
- Are considered electromagnetic waves which are waves that can travel through matter or empty space where matter is not present.
- Light waves are the only part of the electromagnetic spectrum that is visible to the human eye.
- Mechanical waves in which the particles of matter in the medium vibrate by pushing together and moving apart parallel to the direction in which the wave travels are called compressional or longitudinal waves.
- The place on the wave that is pushed together is called the compression and the place that is moving apart is the rarefaction.
- Examples of mechanical compressional/longitudinal waves might include sound waves and some seismic waves.
- Mechanical waves in which the particles of matter in the medium vibrate by moving back and forth and perpendicular (at right angles) to the direction the wave travels are called transverse waves.
- The highest point of a transverse wave is the crest and the lowest point is called a trough.
- Examples of mechanical transverse waves might include some waves in a slinky spring, waves on a rope, strings in a musical instrument, and some seismic waves
- Light waves are transverse waves that can travel without a medium through empty space.
Sound waves are mechanical waves that do require a medium such as air to transmit energy and cannot be transmitted in a vacuum.
Electromagnetic waves such as visible light and radio waves can be transmitted in a vacuum because they do not require a medium to transmit energy.
- Explore the mechanisms (the oscillations of the fields) by which energy is transferred through empty space.