Solution: Solution: (1)① The wave propagates to the right. According to the uphill and downhill method, it is known that point A moves upward, and the direction of movement of point A is shown in the waveform diagram.

② According to the periodicity of the wave, the waveform at (t+ 14T) is consistent with the waveform at 14T, that is, the original waveform is shifted to the right by 14 wavelength, as shown in the right figure.

(2)① The optical paths passing through P 1, P2, P3 and P4 are as shown in the figure.

② According to the law of refraction, n = sinisin γ.

De: sinc = 1n = sin γ sini。

So the critical angle is: c = arcsin γ sini.

Propagation speed of light in medium: v = cn = sin γ sinic.

Answer: (1)①② The picture is from the above picture.

(2)① The optical paths passing through P 1, P2, P3 and P4 are shown in the right figure.

② The expression of critical angle for total reflection of light in medium is c = c = C=arcsinsinγsini, and the propagation speed of light in medium is sinγsinic.