Which unit of measurement is used to express the energy of gamma rays?

The unit of measurement used to express the energy of gamma rays is the kilo electron volt (keV). This unit reflects the amount of energy that an electron gains when it is accelerated through an electric potential difference of one thousand volts. In the context of gamma rays, which are a form of electromagnetic radiation, keV is a suitable unit because it directly conveys the energy levels associated with these high-frequency photons.

Gamma rays typically fall within the range of hundreds of kiloelectron volts up to several mega electron volts (MeV), making keV an effective unit for measuring their energy. The usage of keV provides a clear understanding of the energies involved, particularly in radiographic testing and other nuclear applications where gamma rays are relevant.

Other units mentioned, like watt (W) and kilowatt (kW), are measures of power rather than energy. Power refers to the rate at which energy is used or transferred, while milliampere (mA) is a unit of electric current, which is not applicable for measuring the energy of gamma rays. Thus, keV is the most appropriate measurement unit for this context.