WAVES W What are waves?

Waves Waves are a disturbance that transfers energy from place to place. What carries waves? A medium is the material through which a wave travels. A medium can be a gas, liquid, or solid.

Not all waves require a medium to travel. If a wave requires a medium to travel we can classify it as a mechanical wave. Examples: Ocean waves, Seismic waves, and Sound waves. If a wave does NOT require a medium to travel we can classify it as an electromagnetic wave. Examples: Visible Light, Ultraviolet Rays, Infrared Rays. They travel from the sun to earth through empty space.

What causes waves? Forces can start a disturbance and cause a wave. Waves are created when a source of energy causes a medium to vibrate. A vibration is a repeated back and forth or up and down motion.

Types of waves Waves are classified according to how they move: 1 Types of waves Waves are classified according to how they move: 1. Transverse waves 2. Compressional or Longitudinal Waves

Transverse wave A wave that moves the medium at right angle to the direction in which the wave is traveling is called a transverse wave. Examples: Ocean waves, S waves (kind of seismic wave). Transverse means across. The highest parts in the wave are called crests the lowest parts are called troughs.

Compressional or Longitudinal Wave The medium vibrates in the same direction as the wave travels. Examples: Sound waves, P waves (a kind of seismic wave). The parts, where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.

Properties of Waves Amplitude Wavelength Frequency Speed

Amplitude Amplitude is the maximum distance the particles of the medium carrying the wave move away from their rest position. The farther the medium moves as it vibrates the larger the amplitude of the resulting waves. The greater the amplitude the greater the amount of energy.

Amplitude of Transverse Waves You can find the amplitude of a transverse wave by measuring the distance from rest position to crest or from rest position to trough.

Wavelength Wavelength is the distance between two identical and closest parts of a wave. The wavelength can be measured in a Transverse wave from crest to crest or trough to trough.

Frequency The number of complete waves that pass a given point in a certain amount of time. Frequency is measured in number of waves per second or Hertz. Frequency and Wavelength are inversely related, the longer the wavelength the lower the frequency, or the shorter the wavelength the higher the frequency. Waves with the longest wavelengths have the lowest frequencies. Waves with the shortest wavelengths have the highest frequencies.

FREQUENCY

Speed Wave’ speed is how fast a wave moves through a medium. Waves in different media travel at different speeds. However, in a given medium and under the same conditions the speed of the wave is constant.

Factors that affect Wave Speed The speed of a wave through a substance is determined by the substance’s physical properties. The speed of light through a medium depends on how the medium interacts with electric and magnetic fields. The speed of Sound waves is affected by the temperature of the medium, a substance’s compressibility and density. Speed of light in a vacuum 299 792 458 m / s.

What Happens When Light Hits an Object? Reflected Refracted Absorbed Transmitted

Reflection Reflection occurs when light hits a surface or barrier through which it cannot pass, and it bounces back. There are ways in which a surface can reflect light: regular reflection and diffuse reflection. Regular reflection occurs when parallel rays of light hit a smooth surface. Diffuse reflection occurs when parallel rays of light hit an uneven surface.

Refraction Occurs when a wave moves from one medium into another medium at an angle, it changes speed as it enters the second medium which causes it to bend. Refraction is the bending of waves due to a change in speed that occurs when a wave goes from one medium to another.

Refraction, Lenses Index of Refraction of a medium is a measure of how much a light ray bends when it enters a medium. The higher the index of refraction of a medium, the more it bends light. Mirage is an image of a distant object caused by the refraction of light. Lens is a curved piece of glass or other transparent material that refracts light. Concave lens is thinner in the center than at the edges and produces an upright image smaller than the object. Convex lens is thicker in the center than at the edges, the type of image formed depends on the object’s position.