Snell's Law

• What does Snell's Law relate to?

  Angle of incidence and angle of refraction

  
• What is the formula for Snell's Law?

  $n_1 \sin \theta_1 =$$n_2 \sin \theta_2$

  
• What does $n_1$ represent in Snell's Law?


  Refractive index of material 1

  
• What does $n_2$ represent in Snell's Law?


  Refractive index of material 2

  
• What do $\theta_1$ and $\theta_2$ represent?


  Angles of incidence and refraction
• From where are angles $\theta_1$ and $\theta_2$ measured?


  From the normal
• What is the relationship between refractive index and critical angle?

  Larger refractive index means smaller critical angle

  
• What happens when the angle of incidence reaches the critical angle?

  Angle of refraction becomes 90°

  
• What occurs when the angle of incidence is less than the critical angle?

  The ray is refracted and exits the material

  
• What occurs when the angle of incidence exceeds the critical angle?

  The ray undergoes total internal reflection

  
• What is the critical angle equation?

  $\sin \theta_c =$$\frac{n_2}{n_1}$

  
• What does total internal reflection require regarding refractive indices?

  Incident refractive index must be greater
• What is the relationship between angles of incidence and reflection during total internal reflection?

  Angle of incidence equals angle of reflection
• How does the refractive index of glass compare to air?

  Refractive index of glass is greater than air
• If the angle of incidence is 39° and the angle of refraction is 25°, what is the critical angle for the glass-liquid boundary?

  65°

  
• Given the refractive index of glass is 1.489, how do you calculate the refractive index of the liquid?

  Use Snell's Law with known angles

  
• What is the significance of the angle of incidence being equal to the critical angle?

  It marks the transition to total internal reflection

  
• How does the path of a light ray change when it enters a less dense medium?

  It refracts away from the normal
• What are the conditions for total internal reflection to occur?

  • Angle of incidence > critical angle
  • Refractive index of incident medium > refractive index of second medium

  
• What are the steps to calculate the critical angle?

  1. Identify refractive indices of both materials.
  2. Use the critical angle equation: $\sin \theta_c =$$\frac{n_2}{n_1}$.
  3. Solve for $\theta_c$.

  
• What are the implications of Snell's Law in optics?

  • Predicts how light bends at interfaces
  • Essential for designing lenses and optical devices
  • Helps understand phenomena like rainbows and mirages