the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)
German physicist who was the first to produce electromagnetic waves artificially (1857-1894)
German physicist who with James Franck proved the existence of the stationary energy states postulated by Bohr (1887-1975)
the act of damaging something or someone
feel physical pain
cause emotional anguish or make miserable
a damage or loss
feelings of mental or physical pain
any physical damage to the body caused by violence or accident or fracture etc.
feel pain or be in pain
hurt the feelings of
psychological suffering
damaged; used of inanimate objects or their value
suffering from physical injury especially that suffered in battle
be the source of pain
cause damage or affect negatively
give trouble or pain to
