# Angle of incidence question

b]1. A light beam coming from an underwater spotlight exits the water at an angle of 68° to the vertical. At what angle of incidence did it hit the air-water interface from below the surface?

2. snell's law n1sin$$\Theta$$1=n2sin$$\Theta$$2

3. sin$$\Theta$$1=1.33(sin68)
After doing this I took the inverse sin of it and it comes up as error on my calculator. I know it should be an easy question but I dont know where I am messing up.

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jgens
Gold Member
It looks like you've got the equation set up wrong. It should read:

$$n_1\sin{(\theta_1)} = n_2\sin{(\theta_2)}$$

Where $n_1 = 1.33$, $n_2 = 1$, and $\theta_2 = 68$.

I knew it would be something dumb, thanks for your help.