Two waves of identical frequency and amplitude superimpose in the same medium. If they meet perfectly in phase (crest meets crest), the resulting amplitude is: MCQ with Answer and Explanation

This is an example of constructive interference. According to the principle of superposition, the resultant displacement is the algebraic sum of individual displacements. If the waves are perfectly in phase, their amplitudes add directly (A + A = 2A). Note that while amplitude doubles, the intensity (which is proportional to amplitude squared) becomes four times greater.