Phthalates are another class of chemicals that are often used in deodorants and antiperspirants that you may want to avoid. Phthalates are used in cosmetics, synthetic fragrances, plastics, body care products and medical goods. They help to dissolve other ingredients and to create a better consistency.
A harmonic is a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave. The term can also refer to the ratio of the frequency of such a signal or wave to the frequency of the reference signal or wave.
Resonance is a condition in which a vibrating system responds with maximum amplitude to a periodic driving force.Mechanical systems will have a number of possible frequencies at which this occurs. These are the system's natural frequencies of vibration.t breaks. So, the resonance frequency is the frequency with which some external source must exert a force (swinging legs, sound wave, wind pushing a bridge, etc.) so that each application of the force adds constructively.