954,969 Contributions. Cod fish is bad if: it has yellow spots and transparent parts on the surface instead of an even, light surface.there is a coating of slime on the surface; the surface should b â¦ e shiny and dry.it has a sharp, strong odor; sea fish should have a fresh, neutral, or weak odor.f the catfish has a strong fishy smell, it has gone bad. You can  also tell by looking at it, if you see areas that appear  discolored, it is likely bad.
Frequency. The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second. The unit of frequency is the hertz (Hz).It is common for kilohertz (kHz), megahertz (MHz) and gigahertz (GHz) to be used when waves have very high frequencies.requency. The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second. The unit of frequency is the hertz (Hz).
1 Hertz is the unit of frequency, and just means how many cycles per second. 2  It is abbreviated as Hz. 3  It is named after Heinrich Hertz, one member of the Hertz family that made many important contributions to physics. 4  In formulas frequency appears as an  f . Hertz is the unit of frequency, and just means how many cycles per second. 2  It is abbreviated as Hz. 3  It is named after Heinrich Hertz, one member of the Hertz family that made many important contributions to physics. 4  In formulas frequency appears as an  f .