Lesson 10 — Refraction

• Refraction
• Middelbare school
• havo, vwo
• Leerjaar 2

Refraction

This lesson

• recap
  
• Refraction in a glass block
  
• total internal reflection — critical angle
  

Goals

• Describe what refraction is
  
• Explain why refraction causes the image of an object to get deformed using a ray diagram
  
• Explain what the refractive index is
• Apply the refractive index
• Explain total internal reflection and the critical angle

what is refraction?

Refraction

• When light goes from one material to another it gets bend according to the refractive index
  

Link

Refraction 

Link

Refraction — The refractive index 

Link

Refractive index

• The capacity for a material to bend light
  

• (The amount that the light gets bend depends on the difference in refractive index between to materials)

refractiveindex=​speedoflightmedium​​speedoflightvacuum​​

refractiveindex=​speedoflightmedium​​speedoflightvacuum​​

n=​v​​c​​

• Refractive index (n) — no unit
  
• Speed of light vacuum (c) — m/s
  
• Speed of light medium (v) — m/s
  

Exercise

See the speed of light in the following materials:

• Speed of light glass: 200 000 000 m/s

• Speed of light water: 225 000 000 m/s

• Speed of light plastic: 190 000 000 m/s
  

Imagine a light ray going from vacuum into one of these materials. Order these  materials on how much they bend the light from strongest to weakest.

Refraction — glass to air

Link

Lower to higher 

refractive index

Higher to lower refractive index

Bends towards the normal line

Bends away from the normal line

Total internal reflection? — Exercise

1. Go to the pet simulation bending light — Intro
   
2. Set the refractive index on the top to glass
   
3. Set the refractive index on the bottom to air
   

• Experiment with the simulation in pairs
  
• Using paragraph 6.7 try to figure out what total internal reflection means
  

Goals

• Describe what refraction is
  
• Explain why refraction causes the image of an object to get deformed using a ray diagram
  
• Explain what the refractive index is
• Apply the refractive index
• Explain total internal reflection and the critical angle