## Math and Physics CR (Old) Ch. 11 Pr #11

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Joined: Sun Sep 10, 2017 4:17 pm

### Math and Physics CR (Old) Ch. 11 Pr #11

Information states that "A light beam...encounters a flat surface...such that the smallest angle the beam makes with the surface is 30*."

The question asks "What is the smallest angle the refracted ray makes with the surface?"

The given answer and explanation state that "In this case the incident angle is 60*, since the problem states that the angle with the horizontal is 30*..."

I don't understand how this is computed nor, semantically, what the difference is between the angle of incidence and the "smallest angle the beam makes with the surface."

Is the relationship a minimum to maximum one? Such that the incident angle must always be maximum to the smallest angle the light makes with the horizontal?
NS_Tutor_Andrew
Posts: 520
Joined: Mon May 23, 2016 1:47 pm

### Re: Math and Physics CR (Old) Ch. 11 Pr #11

Thanks for the excellent question. Basically, this Q is just asking you to use geometry to distinguish between angle to the horizontal & angle to the normal. I've attached a drawing that should help clarify things.
forum question.png