"Eyes and Glasses" Lenses and Their Applications PPT Courseware 4

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"Eyes and Glasses" Lenses and Their Applications PPT Courseware 4

1. The principle of seeing with the human eye: imaging through a convex lens similar to a camera

The cornea and lens work together as a convex lens.

The retina is equivalent to a light screen.

Objects appear as inverted, reduced real images on the retina

2. The principle of how the human eye can see distant and near objects clearly: the adjustment function of the lens

The process of seeing objects clearly with the human eye——

Optic nerve cells are stimulated by light and transmit this signal to the brain, and we see objects.

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, the refractive power is too strong, or the eyeball is too long in the front-to-back direction, and light from far away is concentrated in front of the retina.

2. Correction:

Wear myopia glasses made of concave lenses.

4. Hyperopia and its correction

1. Cause:

The lens is too thin, the refractive power is too weak, or the eyeball is too short in the front-to-back direction, and light from near areas is concentrated behind the retina.

2. Correction:

Wear farsighted glasses made with convex lenses. (reading glasses)

Innovation exploration one:

Through the adjustment of the lens, the eye can make objects of different distances form clear images on the retina. The two extreme points of eye adjustment are called the far point and the near point. The far point of a normal eye is at infinity, and the near point is about 10cm. The distance at which normal eyes can observe nearby objects most clearly without fatigue is about 25cm, which is called the photopic distance. Read the words in the book, measure your photopic distance, and compare it with other students: Is the photopic distance the same for normal eyes and myopic eyes? What are the rules?

1. The clear vision distance of myopic eyes is shorter than that of normal eyes;

2. The photopic distance of different myopic eyes is also different;

3. The photopic distance of the hyperopic eye is longer than that of the normal eye.

Innovation exploration two:

There are several reading glasses here. Please study the scientific world "The power of glasses" on page 64 of the textbook by yourself, and then discuss in groups to design an experimental plan for measuring the power of reading glasses.

Knowledge:

1. The power of the lens: the reciprocal of the focal length of the lens. (φ)

Formula: φ=1/f (f is the focal length of the lens)

Unit: φ: m-1 f: m

2. Glasses power = lens power × 100

3. The power of a convex lens is expressed as a positive number, and the power of a concave lens is expressed as a negative number.

practise

1. The human eye is a "magical camera". In the picture below, _______ is equivalent to the lens of the camera. It can ____________ (fill in "converge" or "divergence") the light on the retina, which is equivalent to the camera. of____________.

2. The picture below is a light path diagram when someone looks at a close object. From the picture, it can be seen that he has _______ eyes (please fill in "myopia" or "hyperopia"). If the thickness of the center of the spectacle lens he wears is 1.7mm, the thickness of the edge of the lens should be ____1.7mm (optional "greater than", "equal to" or "less than").

3. After the light is refracted by the lens of the eyeball, it can be imaged on the retina. The picture below is a normal eyeball imaging model designed by Xiaoliang. The following description is correct ( )

A． Convex lens is equivalent to retina

B. Candles are equivalent to lenses

C. Convex lens is equivalent to lens

D. The light screen is equivalent to the lens

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For more information about the PPT courseware "Lens and Its Applications in Eyes and Glasses", please click the "Lens and Its Applications ppt Eyes and Glasses ppt" tag.

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"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: 2024-07-11

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

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