The general form of Snell's Law is used to describe the change in direction of light when it moves between any two media and not just out of air.

 

Snell's Law:  The general form of Snell's Law relates the ratio of the indexes of refraction to the ratio of the sine of the angles of incidence and refraction.

 

Expressed as an equation,

 

 

Quantity Symbol SI Unit
refractive index of the first medium n 1 coefficient (no units)
refractive index of the second medium n 2 coefficient (no units)
angle of incidence (measured from the normal) θ 1 degrees
angle of refraction (measured from the normal) θ 2 degrees

 


  





Self-Check

Answer the following self-check (SC) question then click the "Check your work" bar to assess your response.

 

SC 2.  

A laser is submerged in oil ( n oil = 1.48) and directed into a pool of water ( n water = 1.33) with an angle of incidence equal to 35.0°.  Calculate the angle of refraction.  Show your calculations and use the Refraction simulation below (Select the hamburger in the bottom right hand corner and select "Full Screen" to verify your answer.


 

   Self-Check Answer

Contact your teacher if your answers vary significantly from the answers provided here.

 

SC 2.  


Given

 

Required

the angle of refraction,  θ 2

 

Analysis and Solution

 

Paraphrase

The angle of refraction is 39.7°.

 

Snell's Law can be expanded when you consider light as a transverse wave. In the expanded form, frequency, wavelength, and speed are related according to the following equation:

 


Read
Read "Snell's Law, Refraction, and Wavelength" on pages 669-670 for a derivation of the equation above based on the transverse wave model of EMR.


Try This
Complete "Practice Problems" 1-4 on page 668 of your textbook and "Practice Problems" 1(a), 1(b), 2, and 3 on page 670 of your textbook.  Note, the index of refraction values are given on page 667.