# Optics Exam 4 and Problem Solutions

**1.** Find the velocity of the light in a medium having refractive index n=2.

**n=c/V**

**2=300000/V**

**V=150000km/h**

**2.** Relative refractive indexes of mediums are n₁,₂=2, n₂,₃=1,5. Find n₁,₃.

**n₁,₂=n₂/n₁=2**

**n₁=n₂/2**

**n₂,₃=n₃/n₂=1,5**

**n₃=1,5n₂**

**n₁,₃=n₃/n₁=1,5n₂/n₂/2=3**

**3.** If the ray follows following path while passing from one medium to another, find the refractive index of medium.
**n₁,₂=n₂/n₁**

UsingSnell’s law

**n₁.sin60⁰=n₂.sin30⁰**

**n₂/n₁=sin60⁰/sin30⁰=√3**

**4.** Find the distance between point K and its image on plane mirror with respect to observer placed at point A.
**happarent=nair/nmedium.hreal**

**happarent=1/3.30cm**

**happarent=10cm**

**5.** Path of the ray S is given below on spherical medium. Find the relation between refractive indexes of these mediums.
As you can see from the picture given below, angles of refracted rays are larger than the angles of incident rays, Thus, relation between the refractive indexed becomes;
**n₁>n₂>n₃**