The wave function (in S.I. units) for an electromagnetic wave is given as:             $\psi (x, t) $= 103 sinp (3 x 106x – 9 x 1014t)             The speed of the wave as:

9 x 1014m/s                                  3 x 108m/s  3 x 1016m/s       3 x 107m/s

3 x 108m/s

$ c = \frac{\omega}{k} = \frac{9\times 10^{14}}{3\times 10^6} = 3\times 10^8 m/s$