Introduction to electromagnetism is a quantity used to determine how a particle will behave in an electric field. There are three possible "types" of charge: positive, negative, and neutral. However, the distinction between positive and negative is by convention only. Electric charge is quantized in units of the elementary charge, formula_1, where a proton has a charge of formula_2 and an electron has a charge of formula_3. The SI unit of charge is the coulomb. The elementary charge formula_1 was first measured by Robert Millikan in his oil drop experiment in which the electric force on the particle is set to exactly counter
Mass-to-charge ratio a scalar property, meaning that it can be either positive (+) or negative (−). The Coulomb (C) is the SI unit of charge; however, other units can be used, such as expressing charge in terms of the elementary charge (e). The SI unit of the physical quantity "m"/"Q" is kilogram per coulomb. The units and notation above are used when dealing with the physics of mass spectrometry; however, the "m"/"z" notation is used for the independent variable in a mass spectrum. This notation eases data interpretation since it is numerically more related to the unified atomic mass unit. The "m"