Two sinusoidal electromagnetic waves of the same angular frequency, ω = 110 rad/s, and oscillating in the same direction are emitted from the same location. the waves are emitted starting at times t1 and t2, respectively, with t2 later than t1 by t2 - t1 = 0.22 s. they are emitted with the same initial phase, φ = 2.1 rad, but have different amplitudes, a1 = 2.4 v/m and a2 = 5.5 v/m, respectively. the time dependence of the waves at their source has the form ei = ai cos(ωt+φ), where t denotes the elapsed time since the start of emission for each wave.