This question already has an answer here:

Two identical waves, of amplitude $A$, have energy proportional to $A^2$. The sum of the energies of these two waves being proportional to $2A^2$.

If these two waves superimpose to form a wave of the same form with amplitude $2A$. The energy of this wave will now be proportional to $(2A)^2 = 4A^2$. This suggests an increase in energy by a factor of $2$, which is a contradiction to the conservation of energy.

How is this rectified please?


marked as duplicate by Community Apr 20 '17 at 9:10

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Browse other questions tagged or ask your own question.