Waves carry energy. Earthquakes can destroy cities. Loud sound can pulverise nerve cells in the inner ear. Intense light can burn; lasers can kill cancer cells.
The
energy carried by a wave is related to its
amplitude squared.
Recall that for systems undergoing simple harmonic motion, the total energy is equal to ½kX2 where k is the force constant, and X is the amplitude of the motion.
The time taken for this transfer of energy is also important. The longer a sound is applied, the more energy it transfers.
The power associated with a wave is expressed in Watts (symbol W) is equal to energy per unit time.
Because waves can be focused on tiny spots, the area to which the energy is transferred is also important.
The intensity of a wave is equal to the power per unit area. This quantity has the unit W m–2.