Why does a convex lens magnify objects and a concave lens shrink objects?
A convex lens, also known as a converging lens, magnifies objects because of its unique shape and the way it refracts light. To understand why a convex lens magnifies objects, let's break it down into a step-by-step explanation:
1. Light refraction: When light passes through a convex lens, it bends towards the center of the lens due to refraction. This bending of light rays is caused by the lens's curved shape.
2. Converging rays: The curved surface of a convex lens causes incoming parallel rays of light to converge or come together. This convergence occurs at a specific point called the focal point.
3. Focal point and focal length: The focal point is where the incoming parallel rays converge after passing through the lens. The distance between the lens and the focal point is known as the focal length.
4. Magnification: When an object is placed beyond the focal point of a convex lens, a magnified virtual image is formed on the opposite side of the lens. The image appears larger than the actual object due to the convergence of light rays.
In the case of a concave lens, also known as a diverging lens, the lens is thinner at the center and thicker at the edges. This shape causes it to diverge or spread out the incoming light rays. Here's how it works:
1. Light refraction: When light passes through a concave lens, it bends away from the center of the lens due to refraction. The lens's thinner center and thicker edges cause the light rays to spread out.
2. Diverging rays: The curved surface of a concave lens causes incoming parallel rays of light to diverge or spread out. This divergence occurs as if the rays are coming from a specific point called the focal point.
3. Focal point and focal length: The focal point of a concave lens is the point from which the diverging rays appear to originate. The distance between the lens and the focal point is known as the focal length.
4. Image formation: When an object is placed in front of a concave lens, the lens causes the light rays to diverge further. This divergence results in a smaller, virtual image that forms on the same side of the lens as the object. The image appears smaller than the actual object due to the spreading out of rays.
To summarize, a convex lens magnifies objects because it converges light rays, causing them to come together and form a magnified virtual image. A concave lens, on the other hand, spreads out light rays, resulting in a smaller virtual image.