What are the causes for the resonance?

Answer:
Resonance is actually the tendency of vibrating body to increase its amplitude when applied frequency becomes equal to its natural frequency. When we apply a frequency equal to the natural frequency of vibrating body (i.e by giving a push to a swing FOR EXAMPLE). This push (force) makes amplitude double. Because Amplitude directly varies with Force but Time Period or Frequency does not change.
First answer by Haseeb Abbas. Last edit by Haseeb Abbas. Contributor trust: 0 [recommend contributor recommended]. Question popularity: 1 [recommend question].