### Correct Option: B. The light slows down and bends towards the normal. #### Detailed Explanation: When light travels from one medium to another, its speed and direction can change due to the different optical densities of the materials involved. In this case, we are considering the transition of light from air (a less dense medium) into water (a denser medium). 1. **Speed of Light in Different Media**: - The speed of light in a vacuum is approximately \(3.00 \times 10^8\) m/s. - In air, the speed is very close to this value, but when light enters water, it slows down significantly. The speed of light in water is about \(2.25 \times 10^8\) m/s. 2. **Refraction**: - Refraction is the bending of light as it passes from one medium to another due to a change in speed. This bending occurs at the interface between the two media. - 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, approximately 1.00), - \(n_2\) is the refractive index of the second medium (water, approximately 1.33), - \(\theta_1\) 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 ray and the normal). 3. **Direction of Bending**: - When light enters a denser medium (like water), it slows down. According to the principles of refraction, this causes the light to bend towards the normal line (an imaginary line perpendicular to the surface at the point of incidence). - Conversely, if light were to move from water to air, it would speed up and bend away from the normal. #### Why Other Options Are Incorrect: - **Option A: The light speeds up and bends away from the normal**: - This is incorrect because when light enters a denser medium (water), it actually slows down, not speeds up. Therefore, it cannot bend away from the normal. - **Option C: The light speeds up and continues in a straight line**: - This option is incorrect because the light does not speed up when entering water; it slows down. Additionally, it cannot continue in a straight line when transitioning between media of different densities. - **Option D: The light slows down and bends away from the normal**: - This option is also incorrect. While it is true that the light slows down when entering water, it bends towards the normal, not away from it. ### Summary: - Light slows down when it passes from air into water due to the higher optical density of water. - The bending of light towards the normal occurs because of the change in speed as it enters a denser medium. - Snell's Law quantitatively describes the relationship between the angles of incidence and refraction based on the refractive indices of the two media. ### Revision Summary: - Light slows down when entering a denser medium (like water). - Light bends towards the normal when moving from a less dense to a more dense medium. - Snell's Law relates the angles of incidence and refraction to the refractive indices of the media. - Understanding the behavior of light at interfaces is crucial for solving problems related to optics.