**Correct Option: B. The angle of incidence is equal to the angle of reflection.** ### Detailed Explanation: When light reflects off a smooth surface, it follows a fundamental principle known as the law of reflection. This law states that: - The angle of incidence (θi) is equal to the angle of reflection (θr). **Definitions:** - **Angle of Incidence (θi):** This is the angle formed between the incoming ray of light and the normal (an imaginary line perpendicular to the surface at the point of incidence). - **Angle of Reflection (θr):** This is the angle formed between the reflected ray of light and the normal. **Visualizing the Concept:** Imagine a flat mirror. When a beam of light strikes the mirror, it hits the surface at a certain angle. If you draw a line perpendicular to the surface at the point where the light hits (this is the normal line), you can measure the angle between the incoming light ray and this normal line. This is the angle of incidence. After the light reflects off the mirror, it will leave at the same angle relative to the normal line, which is the angle of reflection. **Mathematically:** The law of reflection can be expressed as: \[ \theta_i = \theta_r \] This relationship holds true for all smooth surfaces, such as mirrors or calm water, where the surface is even and allows for clear reflection. ### Why Other Options Are Incorrect: **A. The angle of incidence is greater than the angle of reflection.** - This statement contradicts the law of reflection. If the angle of incidence were greater than the angle of reflection, it would imply that the light is bending or refracting, which is not the case in reflection. Reflection maintains the equality of angles. **C. The angle of incidence is less than the angle of reflection.** - Similar to option A, this statement also contradicts the law of reflection. If the angle of incidence were less than the angle of reflection, it would again suggest a bending of light, which does not occur in reflection. **D. The angle of incidence varies depending on the color of the light.** - This statement is misleading. The angle of incidence does not depend on the color of the light. The law of reflection applies universally to all wavelengths of light. While different colors of light can have different speeds in various media (which leads to refraction), reflection itself is governed by the same angle relationship regardless of color. ### Common Pitfalls: - **Confusing Reflection with Refraction:** Students often mix up the laws of reflection and refraction. Remember, reflection involves the same angle for incidence and reflection, while refraction involves bending of light and different angles. - **Ignoring the Normal Line:** When measuring angles, always ensure you are measuring from the normal line, not the surface itself. - **Assuming Surface Roughness Affects Reflection Angles:** While rough surfaces scatter light and can create diffuse reflection, the law of reflection still holds true for each individual ray reflecting off a small area of the surface. ### Revision Summary: - The angle of incidence is always equal to the angle of reflection (θi = θr). - This principle applies to smooth surfaces like mirrors. - The normal line is crucial for measuring angles accurately. - Reflection is independent of the color of light; it applies universally to all wavelengths.