(1) As shown in the figure, since the incident angle of light at point D is 60, SIN 60 > 1N is totally reflected, it is concluded from the reflection law and geometric knowledge that ∠ 4 = 30,

So sin∠5 sin∠4 =n?

The solution is sin ∠ 5 = 2 2.

Therefore, the refraction angle of the light exiting the prism from the BC plane is about 5 = 45.

(2) Let the time required for light to travel from point O to point E be t, then

t= OD+DE v，v= c n

Judging from mathematical knowledge, OD= 3 a, DE = 233 a.

T = 56a3c can be obtained from the above categories.

Answer: (1) The optical path diagram is as shown in the figure, and the refraction angle is 45 degrees.

(2) When light enters the prism, it takes 56a3c to enter the air for the first time.