Question

Angle which is formed between normal ray and ray entering a medium is known as

• A. critical angle
• B. angle of incidence
• C. angle of reflection
• D. angle of refraction

Hint:

Incident ray with normal gives angle of incidence. Refracted ray with normal gives angle of refraction.

Answer 1

The Correct Option is B

Concept:
When light falls on a surface separating two media, different rays and angles are defined. The ray coming toward the surface is called the incident ray. A perpendicular line drawn at the point of incidence is called the normal. The angle between the incident ray and the normal is called the angle of incidence.

Step 1: Identify the ray mentioned in the question.
The question says: \[ \text{ray entering a medium} \] This means the ray is approaching the boundary surface from one medium and entering another medium. This ray is the incident ray.

Step 2: Define the angle.
The angle between the incident ray and the normal is: \[ \text{Angle of incidence} \] It is generally represented by: \[ i \]

Step 3: Differentiate from other angles.
Angle of reflection is the angle between reflected ray and normal. Angle of refraction is the angle between refracted ray and normal. Critical angle is the angle of incidence in denser medium for which angle of refraction becomes \(90^\circ\).

Step 4: Check the options.
Option (A) critical angle is incorrect.
Option (B) angle of incidence is correct.
Option (C) angle of reflection is incorrect.
Option (D) angle of refraction is incorrect. Hence, the correct answer is: \[ \boxed{(B)\ \text{angle of incidence}} \]