Longitudinal waves show areas of compression and rarefaction : compressions are regions of high pressure due to particles being close together. rarefactions are regions of low pressure due to particles being spread further apart.

A compression is when the particles in the medium through which the wave is traveling are closer together than in its natural state, that is, when their density is greatest. A rarefaction is when these particles are further apart than is normal, or when their density is least.

An example of a medium is a metal spoon sitting in a cup of hot tea that is too hot to touch. An example of a medium is a newspaper from the combined media form of newspapers, television, magazines, radio and the Internet. Mechanical waves are waves that require a medium. One example of a mechanical wave is sound.

In terms of traveling waves (light included) the “medium” is the material the wave is passing through. Air, glass, et cetera.

Refractive Index (Index of Refraction) is a value calculated from the ratio of the speed of light in a vacuum to that in a second medium of greater density. The refractive index variable is most commonly symbolized by the letter n or n’ in descriptive text and mathematical equations.

(a) Transparent medium : The medium that allows light to pass through is called transparent medium. Examples: Air, glass, pure water. (b) Translucent medium : The medium through which light rays can pass partially is called translucent medium. Examples: Fog, ground glass.

Types of optical mediums

• Homogeneous medium.
• Heterogeneous medium.
• Transparent medium.
• Translucent medium.
• Opaque body [Mainly two types of Optical Mediums (1)Homogeneous and (2) Heterogeneous.

Light travels slower in a medium than it does in a vacuum, and the speed is proportional to the density of the medium. This speed variation causes light to bend at the interface of two media — a phenomenon called refraction.

A sound wave needs a medium to travel A sound wave travels in the form of a longitudinal wave and it requires a material medium for its propagation. Sound always originates from some vibrating body.

Radiation. Radiation is a mode of heat transfer which takes place through vacuum and hence, does not need a physical medium.

In electromagnetic waves, energy is transferred through vibrations of electric and magnetic fields. In sound waves, energy is transferred through vibration of air particles or particles of a solid through which the sound travels. In water waves, energy is transferred through the vibration of the water particles.

Among the given options, silver is the best conductor of heat. Due to this reason, silver is used in many heat transfer applications.

It stops rising when it has cooled to the same temperature as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward moving exterior is caused by colder air being displaced at the top of the thermal. Another convection-driven weather effect is the sea breeze.

Everyday Examples of Convection boiling water – When water boils, the heat passes from the burner into the pot, heating the water at the bottom. This hot water rises and cooler water moves down to replace it, causing a circular motion. ice melting – Ice melts because heat moves to the ice from the air.