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## Homework Statement

A light ray enters the plastic block in the illustration at an angle of 33.0° and then exits the opposite side. The long side of the block has a length of 0.670 m and its index of refraction is 1.70. For how much time is the light ray inside the block?

https://www.physicsforums.com/attachment.php?attachmentid=15094&stc=1&d=1219187822

## Homework Equations

Snell's law:

n

_{i}sin[tex]\theta[/tex]

_{i}=n

_{r}sin[tex]\theta[/tex]

_{r}

n=index of refraction

[tex]\theta[/tex]=incident angle from normal

n plastic=1.70

n air = 1.00

## The Attempt at a Solution

According to Snell's law:

(1.70)*sin(33)=(1.00)*sin([tex]\theta[/tex])

0.92588636=sin([tex]\theta[/tex])

arcsin(0.92588636)=[tex]\theta[/tex] = 67.8023923 degrees

And the speed of light is 2.998*10^8 m/s.

But after that I am not sure where to proceed! Can anyone help me figure this one out?