The correct option is **C. Angle of Incidence**. ### Detailed Explanation: 1. **Understanding the Terms**: - **Normal Line**: This is an imaginary line that is perpendicular (at a 90-degree angle) to the surface at the point where the light ray strikes. It serves as a reference line for measuring angles. - **Incoming Ray**: This is the ray of light that approaches the reflective surface before it strikes it. - **Reflected Ray**: This is the ray of light that bounces off the reflective surface after striking it. 2. **Defining the Angle of Incidence**: - The **angle of incidence** is defined as the angle formed between the incoming ray and the normal line at the point of incidence. It is denoted by the symbol \( i \). - According to the law of reflection, the angle of incidence is equal to the angle of reflection, which is the angle between the reflected ray and the normal line. 3. **Why Option C is Correct**: - The question specifically asks for the angle between the incoming ray and the normal line. By definition, this is precisely what the angle of incidence is. Therefore, option C is the correct answer. ### Why the Other Options are Incorrect: - **A. Angle of Reflection**: - The angle of reflection is the angle between the reflected ray and the normal line. It is not the angle between the incoming ray and the normal, which is what the question is asking for. Thus, this option is incorrect. - **B. Angle of Refraction**: - The angle of refraction occurs when light passes from one medium to another (for example, from air into water) and bends. It is the angle between the refracted ray and the normal line. Since the question pertains to reflection, this option is not applicable and therefore incorrect. - **D. Angle of Deviation**: - The angle of deviation refers to the angle between the direction of the incoming ray and the direction of the outgoing ray after refraction or reflection. This term is not relevant to the context of the question, which focuses on the angle of incidence. Hence, this option is also incorrect. ### Summary of Key Concepts: - The **angle of incidence** is the angle between the incoming ray and the normal line at the point of incidence. - The **law of reflection** states that the angle of incidence is equal to the angle of reflection. - The **normal line** is crucial for measuring angles in optics, as it provides a reference point. - Understanding these definitions is essential for solving problems related to reflection and refraction in physics. ### Revision Summary: - The angle of incidence is the angle between the incoming ray and the normal line. - The angle of reflection is equal to the angle of incidence. - The normal line is perpendicular to the surface at the point of incidence. - The angle of refraction and angle of deviation are not relevant to the question about the angle of incidence.