# Total internal reflection diagram

1. Mar 23, 2004

### phy

ok, i need help with this one question. the diagram that goes with this question is at the following website: http://courseweb.edteched.uottawa.c...lems/PHY1102A-Assignment 4_files/image005.jpg

i tried attaching it but it was too big. ok so here it is:
A ray of light falls on a rectangular glass block (n = 1.5) that is almost completely submerged in water (n = 1.33) as shown in the figure above. (a) Find the angle theta for which total internal reflection just occurs at point P. (b) Would total internal reflection occur at point P for the value of theta found in (a) if the water were removed? Explain.

for part a), i used the equation sin (theta) = n2/n1 and said that n2=1.33 and n1=1.5. this gave me a value for theta being 62degrees. is that it or is there more? thanks a lot.

2. Mar 24, 2004

### gnome

There's more.

1. You didn't finish part (a). You found the value for $$\theta_1$$, not $$\theta$$ (see drawing).

2. You didn't give any answer to part (b).

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