When the light is vertically incident on AB, the light path diagram is as shown in the figure.

From the geometric relationship, we can get: ∠ I 1 = 30, ∠ R 1 = 45.

According to the law of refraction, n = sin ∠ r 1sin ∠ i 1-①.

Solution: n = 2

P is reflected by AC surface and emitted vertically from BC. The light path is as shown in the figure. According to the geometric relationship, we can get the following: ∠ i3 = ∠ I' 3 = 60.

∠r2=30

According to the law of refraction: n = sin ∠ i2sin ∠ R2-②.

Solution: ∠ I2 = 45.

A: The angle value of light PO is 45.