A source produces 15 crests and 15 troughs in 3 sec. when the second crest is produced,the first is 2cm away from the source.Calculate the wavelength,frequency and the wave speed Share with your friends Share 1 Sonu Kumar Singh answered this 2 View Full Answer A.b.kanika answered this time period T = 1 ÷ frequency sec. Wavelength = 2 cm. Number of waves produced per second = 15/3= 5. So Frequency = 5 Hz. Speed of the wave = frequency* wavelength = 5 * 2 = 10 cm/sec. 1