Optics: Lenses Quiz

Lenses

• Lenses are transmissive optical devices, focusing or dispersing light by refraction
• When light passes through a lens, its direction changes due to refraction
• Lenses can either converge or disperse light
• Lenses are used in various optical devices, including eyeglasses, microscopes, telescopes, and cameras

Concave Lenses

• These lenses are thicker at the edges and thinner in the middle
• When light passes through, refraction causes the light rays to spread out
• They create an upright, smaller image of the object, which is why they are used to correct nearsightedness
• Rays from distant objects need to spread out before reaching the eye, which concave lenses accomplish by diverging the rays
• This helps nearsighted people see distant objects more clearly

Convex Lenses

• These lenses are thinner at the edges and thicker in the middle
• They refract light inward, converging the rays at a focal point
• Used to correct farsightedness by converging light rays to bring a clear focus onto the retina
• They can magnify objects, as light rays are focused closer together, making them appear larger
• Microscopes and eyeglasses often use convex lenses due to their ability to magnify or resolve.
• Modern microscopes employ multiple lenses to achieve greater magnification (e.g., 40x or more).