Physics - Refraction
Can Tue Chi
TABLE OF CONTENTS
01
02
03
04
Refractive
index
Diagram
for A
Speed of
light
Critical
angle
Refractive index of Mystery A
-
-
The other material: air (n=1)
Angle of incidence = 60°
Angle of refraction = 20°
Refractive index of Mystery A:
𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐴
sin 60 𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐴
=
=
𝑛𝑎𝑖𝑟
sin 20
1
➜ 𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐴 = 2.5
(rounded to 2 significant figures)
Refractive index of Mystery B
-
The other material: water (n=1.33)
Angle of incidence: 55°
Angle of refracted: 50°
Refractive index of B:
𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐵
𝑠𝑖𝑛 55 𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐵
=
=
𝑛𝑤𝑎𝑡𝑒𝑟
𝑠𝑖𝑛 50
1.33
1.33 x 𝑠𝑖𝑛 55
➜ 𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐵 =
= 1.4
𝑠𝑖𝑛 50
(rounded to 2 significant figures)
Diagram for Mystery A
Speed of light
Speed of light in Mystery A:
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑣𝑎𝑐𝑢𝑢𝑚
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐴
3 x 108
⟺ 2.5 =
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐴
3 x 108
⟺ 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐴 =
2.5
Speed of light in Mystery B:
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝑣𝑎𝑐𝑢𝑢𝑚
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐵
3 x 108
⟺ 1.4 =
𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐵
3 x 108
⟺ 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛 𝐵 =
1.4
n=
n=
= 1.2 x 108 (m/s)
= 2.14 x 108 (m/s)
Calculate the Critical angle
Mystery A (in the air)
n=
1
𝑠𝑖𝑛𝑐
⟺ 𝑠𝑖𝑛𝑐 =
1
𝑛
=
1
2.5
1
)
2.5
⟺ critical angle = 𝑠𝑖𝑛−1 (
= 23.6°
Calculate the Critical angle
Mystery B (in the water)
𝑛𝑤𝑎𝑡𝑒𝑟
𝑛𝑚𝑦𝑠𝑡𝑒𝑟𝑦 𝐵
⟺ 𝑠𝑖𝑛𝑐 =
= 𝑠𝑖𝑛𝑐
1.33
1.4
1.33
)
1.4
⟺ critical angle = 𝑠𝑖𝑛−1 (
= 71.8°
Thanks for Listening!