The correct option is **B. To diverge light rays, creating a virtual image**. ### Detailed Explanation: 1. **Understanding Concave Lenses**: - A concave lens is a type of lens that is thinner at the center than at the edges. It is also known as a diverging lens because it causes parallel rays of light that enter the lens to spread out or diverge. 2. **How Concave Lenses Work**: - When parallel light rays (such as those from a distant object) pass through a concave lens, they refract (bend) outward. The lens causes the light rays to diverge as if they are emanating from a point behind the lens, known as the virtual focal point. - The focal point of a concave lens is virtual because the light rays do not actually converge at this point; instead, they only appear to come from it when traced backward. 3. **Creating Virtual Images**: - When an object is placed in front of a concave lens, the light rays coming from the object pass through the lens and diverge. The brain interprets these diverging rays as coming from a point behind the lens, thus forming a virtual image. - This virtual image is upright and smaller than the actual object, which is useful in various optical instruments like eyeglasses for nearsightedness. ### Why Other Options Are Incorrect: - **A. To converge light rays to a focal point**: - This statement describes the function of a convex lens, not a concave lens. A convex lens converges light rays to a real focal point, while a concave lens diverges them. - **C. To magnify objects without distortion**: - While concave lenses can create virtual images that may appear larger than the object, they do not magnify objects without distortion. The images produced are typically smaller and can be distorted depending on the lens's shape and the object's distance from the lens. - **D. To reflect light back to its source**: - Concave lenses do not reflect light; they refract it. Reflection is a property of mirrors, not lenses. A concave lens allows light to pass through and diverge rather than reflecting it. ### Formulas and Concepts: - **Lens Formula**: The relationship between the object distance (u), image distance (v), and focal length (f) for lenses is given by the lens formula: \[ \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \] - For a concave lens, the focal length (f) is considered negative. - **Magnification (m)**: The magnification produced by a lens is given by: \[ m = \frac{h'}{h} = -\frac{v}{u} \] - Where \( h' \) is the height of the image, \( h \) is the height of the object, \( v \) is the image distance, and \( u \) is the object distance. ### Common Pitfalls: - Confusing concave lenses with convex lenses is a common mistake. Remember that concave lenses diverge light, while convex lenses converge it. - Misunderstanding the nature of virtual images; they cannot be projected onto a screen as they do not exist in real space. ### Revision Summary: - Concave lenses diverge light rays, creating virtual images. - They are thinner at the center and cause parallel rays to spread out. - The images formed are upright and smaller than the object. - Remember the lens formula and magnification concepts for calculations involving lenses.