# Need help with angle of incidence of light through a prism

## Homework Statement

The direction of the ray of light enters equilateral 60° glass prism normal to the surface as shown in attached image
refracted index of the prism material for the violet light is 1.651

(a) What is the angle of incidence on the surface A-B?
(b) Does total internal reflection occur?
(c) Draw a ray diagram to show how light passes through
the prism

## Homework Equations

critical angle-----sin i c= 1/n

## The Attempt at a Solution

My attempt
a) critical angle
sin= 1/1.651
= 37.3°
Not sure if its 90° for the incidence for side A-B

b) Total internal reflections occur because the angle of incidence is greater
then the critical angle

c) i also attached my attempt to the image.

thank you any help would be great

#### Attachments

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The calculation seems correct, but the way you expressed it is confusing.
You wrote
"sin= 1/1.651
= 37.3°"

You should have written
"sin θc= 1/1.651
θc = 37.3°"

• 1 person
The calculation seems correct, but the way you expressed it is confusing.
You wrote
"sin= 1/1.651
= 37.3°"

You should have written
"sin θc= 1/1.651
θc = 37.3°"
thank you any chance you can tell me if my ray diagram in the picture attached is correct?

ehild
Homework Helper
thank you any chance you can tell me if my ray diagram in the picture attached is correct?
No.

Note that the angle of incidence is defined as the angle the ray encloses with the normal of the surface.
At totalreflecton, the ray is reflected from the surface AB inside the prism, and is incident onto an other side, and then leaves the prism.

ehild