Physics

The photoelectric effect is the propensity of high energy electromagnetic radiation to eject electrons from a given material. The photoelectric effect has been utilized in devices called photocells, consisting of two electrodes in a sealed vacuum tube. By coating one electrode (the photocathode) with a alkali metal of low work function, a photo current could be generated even from visible light. Work function is the minimum energy needed to remove an electron from the surface of a material.

Application of temperature changes in the atmosphere is in adiabatics, or temperature change which are caused by compressing or allowing air to expand.

Relative humidity is expressed as percentage.

A galvanometer is converted into a voltmeter by connecting with high resistance.

Friction is caused by the irregularities on the two surfaces in contact.