The speed of light in a certain substance is 85% of the value in a vacuum. What is the index of refraction of this substance?

Question

         the physics

Answer 1

• Index of Refraction is abbreviated as "n"
• Speed of light in a vacuum is abbreviated as "c"
• Speed of light in a material is abbreviated as "v"
• n = c/v
• The question is asking for the value of "n," given that c=c, and v=0.85c
• n = c/0.85c ≅ 1.18 (The "c's" cancel out).

Answer 2

v = c/n

 

n = c/v = c/(0.85c) = 1/0.85 ≅ 1.176