Write the practical examples of resonance.

Explanation

It is possible for a building, a bridge or airship has several natural frequencies.
Examples of Resonance :
(1) Soldiers marching on a suspended bridge are advised to go out of steps, because during marching periodic external force acting and if frequencies of force and natural frequencies of bridge become same then resonance occur and amplitude becomes large and hence bridge breaks.
(2) When a bridge is designed, care is taken so that the frequencies of the external force due to the gusts of wind and natural frequencies of that bridge do not become equal or nearly equal. If it becomes equal bridge breaks.
(3) In an earthquakde, low and high rise structures remain less affected while medium high structures fall down as natural frequencies of low rise structures are to be higher and those of high structures are to be lower than the frequency of the seismic waves.