1. sin i sin r n Using Snell’s Law sin 𝑖 sin 𝑟 =𝑛 x
Example 1:
Light passes from air to perspex (n=1.49), with an angle of incidence of 52°. What is the angle of refraction?
Step 1 – rearrange the equation to give r.
sin 𝑖 𝑛 = sin 𝑟
Step 2 – plug the numbers in.
sin 52° = sin 𝑟
Step 3 – calculate sin i.
= sin 𝑟
Step 4 – calculate the fraction.
0.52 = sin r
Step 5 – eliminate the sine.
0.52 x sin-1 = (sin r) x sin-1
052 x sin-1 = r
Step 6 – last calcuation!
31.33 = r
Step 7 – and breathe!
Snell’s Law
sin 𝑖 sin 𝑟 =𝑛
sin i
sin r n x
sin i
sin r n x
Index of Refraction for some common substances:
Water: Diamond Flint Glass 1.67 Cubic Zirconia Pyrex 1.47 Plastic Polycarbonate 1.58
A light ray approaches a crown glass block at 49° and refracts at 28.1°. What is the refractive index of the crown glass block?
If n=1.3 and i=23°, what is the angle of refraction?
If n=1.1 and r=4°, what is the angle of incidence?
If i=34° and n=1.4, what is r?
If r=20.3° and i=50, what is the refractive index? Compare your answer to the table above; what is the substance that refracted the light?
Write a question (and answer) that asks for i.
Write another two questions for n and r.

2. sin i sin r n Using Snell’s Law sin 𝑖 sin 𝑟 =𝑛 x
Example 1:
Light passes from air to perspex (n=1.49), with an angle of incidence of 52°. What is the angle of refraction?
Step 1 – rearrange the equation to give r.
sin 𝑖 𝑛 = sin 𝑟
Step 2 – plug the numbers in.
sin 52° = sin 𝑟
Step 3 – calculate sin i.
= sin 𝑟
Step 4 – calculate the fraction.
0.52 = sin r
Step 5 – eliminate the sine.
0.52 x sin-1 = (sin r) x sin-1
052 x sin-1 = r
Step 6 – last calcuation!
31.33 = r
Step 7 – and breathe!
Snell’s Law
sin 𝑖 sin 𝑟 =𝑛
sin i
sin r n x
sin i
sin r n x
Index of Refraction for some common substances:
Water: Diamond Flint Glass 1.67 Cubic Zirconia Pyrex 1.47 Plastic Polycarbonate 1.58
A light ray approaches a crown glass block at 49° and refracts at 28.1°. What is the refractive index of the crown glass block? 1.6
If n=1.3 and i=23°, what is the angle of refraction? 17.4°
If n=1.1 and r=4°, what is the angle of incidence? 3.78°
If i=34° and n=1.4, what is r? 23.54°
If r= 20.3° and i=50°, what is the refractive index? Compare your answer to the table above; what is the substance that refracted the light? N = 2.20 = Cubic Zirconia
Write a question (and answer) that asks for i.
Write another two questions for n and r.