Distance between consecutive nodes is computed as d = lambda / 2 , where 'lambda ' is the wavelength so that lambda = 2 x d = 2 x 21.9 = 43.8 cm = 0.438 m further frequency n = 1/T = 2.13 / 3.65 = 0.5835 Hz then speed of wave V = lambda x n = 0.438 x 0.5835 = 0.2556 m/sec = 25.56 cm/sec
J.J. Thomson discovered electrons and noticed that an atom can be divided. Also, he concluded atoms are made of positive cores and negatively charged particles within it.