Why can a magnifying glass start a fire? What are the three characteristics of a magnifying glass?

In daily life and scientific research, the human eye has a certain limitation in its ability to focus. By using a magnifying glass, you can put an object in front of your eyes and outside the magnifying glass to see an upright and enlarged virtual image. The magnifying glass can be used to magnify the viewing angle. Why can a magnifying glass start a fire? Do you know?

Contents of this article

1. Why can a magnifying glass start a fire?

2. What is a magnifying glass?

3. What are the three characteristics of a magnifying glass?

Why can a magnifying glass start a fire?

Because the lens of the magnifying glass is a convex lens, it has a focusing effect. Therefore, when light is directly irradiated into the magnifying glass, it will focus the light on its surface into a beam, and when it reaches the ignition point of the paper, it will burn. When light enters different media, it will be refracted. That is to say, the distance traveled by the light emitted or reflected by the object after passing through the magnifying glass is much shorter than before.

A magnifying glass is an instrument that can be used to observe the subtle details of an object. It is a simple visual optical instrument and a converging lens with a focal length less than the clear vision distance of the eye. The reason why people can see objects is that the object can form an angle on the retina of the human eye that is proportional to the angle between the object and the eye. If the viewing angle becomes larger, the image formed in the eye will also be larger, and every subtle detail of the object can be accurately seen. Moving the object closer to the eye can increase the person's viewing angle, but the focusing ability of the human eye is limited. By using a magnifying glass, placing the object in front of the eye and placing the object outside the magnifying glass at the same time, you can see an upright and enlarged virtual image, and using a magnifying glass can achieve the purpose of enlarging the viewing angle.

What is a magnifying glass?

A magnifying glass is a convex lens. It is a simple visual optical device used to observe tiny details of an object. It is a converging lens with a focal length much smaller than the eye's visual distance. The size of the image of an object on the retina of the human eye is proportional to the angle (angle of view) of the object to the eye.

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In order to see tiny objects or details of objects clearly, it is necessary to move the objects closer to the eyes, which can increase the visual angle and form a larger real image on the retina. However, when the object is too close to the eye, it cannot be seen clearly. In other words, to see the smallest details clearly, not only should the object have a large enough angle to the eye, but also the appropriate distance should be taken. Obviously, for the eyes, these two requirements are mutually restricted. If a convex lens is placed in front of the eye, this problem can be solved. The convex lens is the simplest magnifying glass, which is a simple optical instrument that helps the eyes observe tiny objects or details.

What are the three characteristics of a magnifying glass?

Thick in the middle, thin at the edge, and transparent. A magnifying glass is a convex lens. A convex lens has the function of magnifying the image of an object. Using a magnifying glass to observe an object can see more details. Magnifying glasses are widely used in many aspects of people's lives and production. The imaging characteristics are magnification, upright, same side, and virtual image.

magnifier:

A magnifying glass is a simple visual optical device used to observe tiny details of an object. It is a converging lens with a focal length much smaller than the clear vision distance of the eye. The size of the image of an object on the retina of the human eye is proportional to the angle (angle of view) of the object to the eye. The larger the angle of view, the larger the image, and the more details of the object can be distinguished. Moving the object closer can increase the angle of view, but it is limited by the focusing ability of the eye. Use a magnifying glass, bring it close to the eye, and place the object within its focus to form a positive virtual image. The function of a magnifying glass is to enlarge the angle of view. Historically, it is said that the use of magnifying glasses was proposed by a British bishop, Grosseteste, in the 13th century.