Example image of eyePlorer eyePlorer map for 'Frequency': Time Cycle Multiplicative inverse Frequency Oscillation Rotation Wave Acoustics Engineering Nu (letter) Optics Physics Radio Heinrich Hertz Hertz SI derived unit Second International System of Units Average Bias of an estimator Expected value Random error Stroboscope Wavelength Division (mathematics) Phase velocity Special case Speed of light Vacuum Monochrome Optical medium Radiant energy Electricity Sensor Electromagnetic radiation Ultraviolet Infrared Infrared homing Night vision Gamma ray X-ray Microwave Radio waves Light-year Terahertz radiation Visible spectrum Absolute threshold of hearing Gas Liquid Solid