Question

What type of lens is a magnifying glass? a) converging d) cylindrical b) diverging e) plain c) spherical

Short answer

Answer: A magnifying glass uses a converging lens (convex lens).

Step-by-step solution

Understanding a Magnifying Glass

A magnifying glass is an optical device that works using a convex lens to form a magnified image of an object. It is typically used for reading small texts, examining objects up close, or for the visually impaired. The lens helps in enlarging images by bending light rays that pass through it so that they converge at the focal point.

Identifying the Correct Lens Type

Given the properties of a magnifying glass, we can eliminate some options that don't fit these characteristics: a) Converging - A converging lens bends light rays to bring them to a single focal point, forming a magnified image. It is also known as a convex lens. d) Cylindrical - Cylindrical lenses have a curvature in only one plane. They do not serve the purpose of magnifying objects like magnifying glasses do. b) Diverging - A diverging lens, or concave lens, spreads out light rays, making objects appear smaller, which is not the desired purpose of a magnifying glass. e) Plain - A plain lens does not have any curvature, so it does not magnify or minimize images. c) Spherical - A spherical lens has a constant curvature throughout its surface, which could be converging (convex) or diverging (concave) in nature.

Selecting the Correct Lens Type

Among the given options, we can conclude that a magnifying glass is a type of: a) Converging lens (convex lens), as it magnifies objects by bending light rays towards a single focal point. This is the optimal lens type for the purpose of a magnifying glass.

Key concepts

Converging Lens

In optics, a converging lens is designed to bend light rays so they come together at a single point, known as the focal point. This lens is usually thicker in the middle than at the edges, which allows it to bend light inward. When light rays pass through a converging lens, such as in a magnifying glass, they converge (come together) to create a larger image of an object. Converging lenses are fundamental in various applications because they can focus light to a point, enhancing images. They are essential in devices like cameras, telescopes, and, of course, magnifying glasses, where clarity and magnification are key elements.

Magnifying Glass

A magnifying glass is a simple optical tool that makes objects appear larger than they are when viewed through its lens. It achieves this by using a convex lens, which is specifically designed to magnify objects. The magnifying glass works by bending incoming light rays so that they converge at the focal point, enhancing the image's size to the viewer. This tool is invaluable for tasks like reading small print or examining intricate details on various objects.

• Key Uses: Reading small texts, observing fine details in crafts or stamps, aiding those with impaired vision.
• Functionality: By enlarging the image using light refraction, it allows for easier visualization of otherwise hard-to-see details.

Convex Lens

A convex lens is an important component in optics due to its ability to cause parallel light rays to converge toward a focal point. Characterized by its outward-curved surface, the convex lens is the opposite of a concave lens, which diverges light. Convex lenses are known for their use in a variety of optical devices that require the magnification of images.

• Structure: The center of a convex lens is thicker than its edges, allowing the lens to bend light rays inward.
• Common Uses: They are utilized in eyeglasses for correcting farsightedness, in cameras for focusing light to form clear images, and in projectors to expand images onto screens.

By changing the way light rays travel, convex lenses are fundamental in creating enlarged virtual images, as seen in a magnifying glass.

Light Refraction

Light refraction is a crucial concept in understanding how lenses, such as those in a magnifying glass, operate. Refraction refers to the bending of light as it passes from one medium to another, changing its speed and direction. This occurs when light moves between materials with different densities, like air and glass.

• Bending of Light: When light enters a denser medium at an angle, it slows down and bends toward the normal line, aiding in focusing light at a particular point within the lens.
• Application: In a magnifying glass, refraction allows the lens to bend light rays inward to converge at a specific focal point, thereby magnifying the viewed object.

This principle is not only at the heart of why lenses work but also vital in the study of optics, affecting everything from everyday glasses to advanced scientific instruments.