Find the value of the angle of emergence from the prism. Refractive index of the glass is square root of 3.
Correct Answer :
60⁰
Solution :
The correct answer is 60⁰.
Step-by-Step Derivation:
1. Identify the angles of the prism:
From the given image, the prism is a right-angled triangle.
The angle at the bottom-left vertex is , and the angle at the bottom-right vertex is .
Therefore, the angle at the top vertex (let's call it ) is:
2. Determine the path of the light ray inside the prism:
The incident light ray enters normally (perpendicularly) to the hypotenuse face of the prism.
Since the angle of incidence at this first surface is , the ray passes straight into the prism without any deviation.
3. Calculate the angle of incidence at the vertical face:
Let be the point of entry on the hypotenuse, and be the point where the ray hits the vertical face.
In the right-angled triangle formed by the top vertex , the entry point , and the point on the vertical face ():
The angle (since the ray enters normally).
The angle at the top vertex is .
Therefore, the third angle in the triangle, , is:
The normal to the vertical face is perpendicular () to that face. Thus, the angle of incidence () on the vertical face is:
4. Apply Snell's Law to find the angle of emergence ():
According to Snell's Law at the interface of the vertical face:
Where:
- The refractive index of glass is
- The refractive index of air is
- The angle of incidence is
Substituting these values:
Since :
Taking the inverse sine:
Thus, the angle of emergence from the prism is 60⁰.
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