The correct option is **B. Convex lens**. ### Detailed Explanation: 1. **Understanding Lenses**: Lenses are optical devices that refract (bend) light to form images. There are two main types of lenses: **convex** and **concave**. - **Convex lenses** are thicker in the middle than at the edges and converge light rays that pass through them. They can produce real or virtual images depending on the position of the object relative to the focal point. - **Concave lenses** are thinner in the middle and thicker at the edges. They diverge light rays and can only produce virtual images. 2. **Magnifying Glass Functionality**: A magnifying glass is essentially a simple convex lens. When an object is placed within the focal length of a convex lens, the light rays coming from the object are refracted in such a way that they appear to diverge from a point behind the lens. This creates a virtual image that is upright and larger than the actual object. 3. **Image Formation by Convex Lens**: - **Object Position**: For a magnifying glass, the object is placed closer to the lens than its focal point (f). - **Ray Diagrams**: If we were to draw a ray diagram: - A ray parallel to the principal axis passes through the focal point on the opposite side after refraction. - A ray passing through the center of the lens continues in a straight line. - The intersection of these rays (or their extensions) on the same side as the object gives us the virtual image. - **Characteristics of the Image**: The image formed is virtual (cannot be projected on a screen), upright (same orientation as the object), and enlarged (larger than the object). 4. **Why Other Options Are Incorrect**: - **A. Concave lens**: A concave lens diverges light rays and can only produce virtual images that are smaller than the object. It cannot create an enlarged image, which is essential for a magnifying glass. - **C. Cylindrical lens**: A cylindrical lens is designed to focus light in one direction (either horizontally or vertically) and is typically used in applications like correcting astigmatism. It does not produce a magnified image in the same way a convex lens does. - **D. Biconcave lens**: Similar to a concave lens, a biconcave lens diverges light rays and produces virtual images that are smaller than the object. It cannot create the enlarged, upright image characteristic of a magnifying glass. ### Summary of Key Points: - A **convex lens** is used in a magnifying glass to produce a virtual, upright, and enlarged image. - The object must be placed within the focal length of the lens for this effect to occur. - Concave and biconcave lenses can only produce smaller virtual images, while cylindrical lenses focus light in one direction and are not suitable for magnification. - Understanding the properties of lenses and how they interact with light is crucial for applications in optics. This thorough understanding of lens types and their image formation characteristics will help you in both theoretical and practical aspects of physics related to optics.