Question

E=180π cos10⁸ (2πt-100y)

Find the (1) frequency in hz, (2) wave number (3) phase velocity (4) wavelength and (5) direction of propagation?

Answer 1

1)

$$f=\dfrac{\omega}{2\pi}=\dfrac{2\pi\ \dfrac{rad}{s}}{2\pi}=1.0\ Hz.$$

2)

$$k=100\ m^{-1}.$$

3)

$$v=\dfrac{\omega}{k}=\dfrac{2\pi\ \dfrac{rad}{s}}{100\ m^{-1}}=0.063\ \dfrac{m}{s}.$$

4)

$$\lambda=\dfrac{2\pi}{k}=\dfrac{2\pi}{100\ m^{-1}}=0.063\ m.$$

5) The wave propagates along $y$-axis.