. . "SDN:P07::CF12N574" . . . . "2009-07-06 15:41:29.0" . "2009-07-06 15:41:29.0" . . . "1" . . "false" . . "accepted"@en . "Frequency is the number of oscillations of a wave per unit time. The radiation frequency can refer to any electromagnetic wave, such as light, heat radiation and radio waves."@en . "SDN:P07::CF12N574" . "" . . . . "1" . "SDN:P07::CF12N574" . . . "radiation_frequency"@en . .