What Big Eyes You Have Magnification

Light reflected from a specimen travels in a straight line to your eyes, which lets you see the specimen at its natural size. You can magnify the size of the specimen by looking at the specimen through a concave lens. A convex lens (Fig. 3-2) is usually made out of glass or plastic; the back of the lens is bent inward and the front is bent outward. It is like looking into a bubble. A magnifying glass is a convex lens.

The specimen is the focal point, which is the place where all the reflected light originates. Light travels in a straight line from the focal point to the lens where the light is bent in a process called refraction. The angle at which light is bent is called the angle of refraction, which is measured in degrees from the natural path of the light. The degree of angle of refraction is determined by the curvature in the lens. The more the lens curves, the greater the angle of refraction.

The image appears larger as the light reflected from the image is refracted. Although the image appears magnified, curvature does distort the image. The amount of distortion depends on the angle of refraction and the distance between the lens and the specimen, which is called the focal length. The point at which light rays meet is called the focal point (Fig. 3-3).

Focal Point

Focal Length

Fig. 3-3. The focal point is where light rays meet.

Focal Length

Fig. 3-3. The focal point is where light rays meet.

You probably saw a distorted image when using a magnifying glass and were able to minimize the distorted effect by changing the distance between the magnifying glass and the specimen.

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