**Correct Option: B. The light ray bends towards the normal and slows down.** ### Detailed Explanation: When light travels from one medium to another, its speed changes depending on the optical density of the mediums involved. In this case, we are considering the transition of light from air (a less dense medium) into water (a denser medium). 1. **Understanding Refraction**: - Refraction is the bending of light as it passes from one medium to another due to a change in its speed. The degree to which light bends is described by Snell's Law, which states: \[ n_1 \sin(\theta_1) = n_2 \sin(\theta_2) \] where: - \( n_1 \) is the refractive index of the first medium (air), - \( n_2 \) is the refractive index of the second medium (water), - \( \theta_1 \) is the angle of incidence (the angle between the incoming light ray and the normal), - \( \theta_2 \) is the angle of refraction (the angle between the refracted light ray and the normal). 2. **Refractive Indices**: - The refractive index of air is approximately 1.00, while the refractive index of water is about 1.33. This means that light travels faster in air than in water. 3. **Behavior of Light at the Interface**: - When light enters water from air, it slows down because water is denser than air. As a result, the light ray bends towards the normal line (an imaginary line perpendicular to the surface at the point of incidence). This bending occurs because the light is transitioning into a medium where it travels more slowly. 4. **Visualizing the Process**: - Imagine a straight line (the light ray) approaching a boundary between air and water. As it hits the boundary, it will change direction towards the normal line. If you visualize the normal line as a vertical line at the boundary, the light ray will come in at an angle and then bend inward towards this line. ### Why Other Options Are Incorrect: - **Option A: The light ray bends away from the normal and speeds up.** - This is incorrect because when light enters a denser medium (water), it does not speed up; it slows down. Additionally, it bends towards the normal, not away from it. - **Option C: The light ray continues in a straight line without bending.** - This option is incorrect because refraction occurs at the interface between two different mediums. The change in speed due to the different densities causes the light to bend rather than continue straight. - **Option D: The light ray bends away from the normal and slows down.** - This option is also incorrect. While it correctly states that the light slows down, it incorrectly claims that the light bends away from the normal. In fact, it bends towards the normal when entering a denser medium. ### Summary of Key Points: - Light slows down and bends towards the normal when entering a denser medium (from air to water). - Refraction is governed by Snell's Law, which relates the angles of incidence and refraction to the refractive indices of the two mediums. - The refractive index of water is greater than that of air, leading to a decrease in speed and a change in direction of the light ray. - Understanding the behavior of light at the interface of different mediums is crucial for solving problems related to optics and refraction.