"Eyes and Glasses" Lenses and Their Applications PPT Courseware 3

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"Eyes and Glasses" Lenses and Their Applications PPT Courseware 3

1. Principle of seeing with human eyes:

The cornea and lens work together as a convex lens.

The retina is equivalent to a light screen.

The light emitted from the object converges on the retina through the lens to form a clear image of the object. The visual nerve cells on the retina are stimulated by the light and transmit this signal to the brain; we can see the object clearly, so the eye is a frame Amazing camera.

2. The principle of seeing distant and near objects clearly with the human eye:

Accommodation of the lens

When the ciliary body relaxes, the lens becomes thinner, allowing light from a distance to converge on the retina, and the eyeball can see distant objects clearly.

When the ciliary body contracts, the lens thickens, allowing light from nearby areas to converge on the retina, allowing the eyeball to see nearby objects clearly.

3. Myopia and its correction

1. Cause:

The lens is too thick and its refractive power is too strong, causing the image to appear in front of the retina.

2. Correction:

Wear myopia glasses made of concave lenses.

microscopes and telescopes

1. What parts does a microscope consist of?

2. What are the functions of the objective lens and eyepiece of a microscope?

3. What parts does a telescope consist of?

4. What are the functions of the objective lens and eyepiece of the telescope?

Viewing angle: The angle between two straight lines drawn from the optical center of the eye to the two ends of the observed object.

Knowledge about perspective: The larger the perspective, the clearer the observation of objects.

The size of the viewing angle is not only related to the size of the object, but also related to the distance from the object to the eye.

Summary: 1. Microscope

(1) Structure: The eyepiece is a convex lens, and the objective lens is also a convex lens

(2) Features: The focal length of the objective lens is relatively short, and the focal length of the eyepiece is relatively long.

(3) Working principle: A nearby object passes through the objective lens to form an inverted, magnified real image (outside the 2 times focal length of the objective lens). This real image happens to fall within the focus of the eyepiece, and passes through the eyepiece to form an upright, magnified virtual image.

Note: The microscope forms an inverted and magnified virtual image relative to the object being observed. Its essence is to magnify the observed object twice, magnification = objective lens magnification × eyepiece magnification.

Summary: 2. Telescope (Kepler Telescope)

(1) Structure: The eyepiece is a convex lens, and the objective lens is also a convex lens

(2) Features: The focal length of the objective lens is relatively long, and the focal length of the eyepiece is relatively short.

(3) Working principle: The distant object passes through the objective lens to form an inverted, reduced real image (between 1f and 2f of the objective lens). This real image happens to fall within the focus of the eyepiece, and passes through the eyepiece to form an upright, enlarged virtual image.

Note: The Kepler telescope forms an inverted and reduced virtual image relative to the object being observed. Its essence is to bring the object under observation closer.

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"Eyes and Glasses" Lenses and Their Applications PPT Courseware 8:

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 8 Learning Objectives 1. What are the main parts of the human eye? 2. How do human eyes see objects? 3. How does the human eye see objects at different distances? 4. What indicates the refractive power of a lens? 5. The formation of myopia..

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 7:

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 7 Think about what you know about your eyes. How do the eyes see these objects? 1. Eyes 1. Structure of the eyeball (1) Lens and cornea: the combined effect is equivalent to A convex lens (2) retina: quite...

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 6:

"Eye and Glasses" Lens and Its Application PPT Courseware 6 Learning Objectives: 1. Understand the structure of the eyeball and how the eye sees objects clearly. 2. Understand the causes of myopia and hyperopia, and know how to correct myopia and hyperopia. 3. Understand the common sense of eye protection. ..

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Update Time: 2024-10-04

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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