Calculating Refractive Index from Critical Angle Measurement?

[aimslin22]

Homework Statement

One method of determining the refractive index of a transparaent solid is to measure the critical angle when the solid is in air. It A_c is found to be 40.5 degrees, what is the index of refraction of the solid?

Homework Equations

nsinA=nsinA

The Attempt at a Solution

1sinA=nsinA

where does the 40.5 go? what does "critical angle" mean?

 

[rock.freak667]

the critical angle is the maximum angle such that the refracted angle is 90 degrees.

Meaning that at i=c,r=90

so that sin(r)/sin(i)=n => sin90/sinc=n
1/sinc=n

for i>c, the light is reflected back into the medium and total internal reflection occurs.

in your question the critical angle is 40.5 degrees.

 

[aimslin22]

Thanks!