Calculations can be based on the relationship among the speed, frequency, and wavelength of light, and on the relationship among luminous flux, illuminance, and distance All frequencies of EM radiation travel at the same speed in a vacuum and consist of an electric field and a magnetic field.

The electromagnetic spectrum is made up of a broad range of frequencies of electromagnetic radiation The types of EM radiation have different frequencies and wavelengths, and different energies and penetrating ability

luminous flux — rate at which light is radiated from a source. magnetic field — the directional lines around a magnetic material that indicates the direction and magnitude of the magnetic force. electric field — a field that tells us the force per unit charge at all locations in space around a charge distribution. electromagnetic spectrum — made up of a broad range of frequencies of electromagnetic radiation.