One optical physics question for the second year of junior high school, and an optical physics quest

Since an annular eclipse is caused by the moon's umbra cone "can't" touch the ground, and a total eclipse is caused by the umbra cone "can" touch the ground, there is no completely illogical situation at the same time where both the ground and the ground can't be touched. The cause of the total annular eclipse is due to the radius of more than 6,000 km of the earth. In the early stages of a total annular eclipse, when the center of the lunar shadow region is in contact with the Earth, the umbra has not yet touched the Earth, so the annular eclipse will be seen first in those places;

After that, the Moon continues to orbit, and when it reaches the middle of the Earth and the Sun, the Moon's umbra can touch the ground at this time, forming a total eclipse, because the area facing the Moon is closer to the Moon (the radius of the Earth) than the area facing the Moon. After that, the moon continues to rotate, the moon's umbra leaves the ground again, and the annular eclipse is seen on the ground again, and finally the moon's shadow leaves the earth, and the solar eclipse ends.

So in summary, it is possible to have both a total and an annular eclipse in the same solar eclipse, but only one eclipse can be seen in the same place on Earth.

A partial solar eclipse can be seen at the same time as the periscopic annular solar eclipse of the moon or at the far point of the total solar eclipse, but the annular solar eclipse and the total solar eclipse cannot occur at the same time, and the correct answer is ab, not AC as the landlord said

The Earth and the Moon do not emit light, only the Sun does. When the Moon orbits between the Earth and the Sun, the three of them are in a straight line, and the Moon's shadow is cast on the Earth. The central part of the shadow is thicker and is called the umbra; The surrounding area is relatively light.

It's called penumbra. If you stand in the umbra, what you see is a total solar eclipse. Because the moon obscures the sun completely; If you stand in the penumbra, what you see is a partial solar eclipse because the Moon only obscures part of the Sun; If the Moon's umbra is not projected on Earth, people in the area enclosed by the umbra extension can still see the edge of the Sun, that is, the Moon only obscures the central part of the Sun, a phenomenon called an annular solar eclipse.

This is related to perihelion and aphelion!! You will understand if you think about it yourself!! As for why not d! You'll have to look at the word "at the same time"!! Hehe.

An annular solar eclipse and a total solar eclipse occur when the observer Moon and Sun are all three in the same straight line, and the Moon is in the middle. Their appearance is related to the distance between the Sun and the Moon, and the proximity of the Sun to the Moon means an annular solar eclipse, and vice versa is not. Therefore, it is impossible for a total solar eclipse and an annular solar eclipse to occur at the same time.

As long as there is a solar eclipse, there will definitely be a partial solar eclipse, but when an annular eclipse occurs, the umbra will not fall on Earth! So there will be no total solar eclipse, and when there is a total solar eclipse, the penumbra will appear around and not in the middle, so there will be no annular eclipse!

Compare the eclipse diagram in the textbook to understand!

It is impossible to see both on the ground, an annular solar eclipse and a total solar eclipse The answer is not ac is ab When the moon is close to the Earth, it is a total solar eclipse When it is far away, it is a partial solar eclipse.

Two pictures! ......

You'll get it.

Definitely. <>

You can understand this by using the linear propagation of light to draw a picture.

The picture is finished for you, and I hope to give points.

The picture upstairs is wrong, mine is the correct solution.

The shade of blue is the range that can be seen.

1. The glass has a certain thickness, and the two sides become two images.

The height of the candle is not on a horizontal line.

2. Connect OC (apostrophe) to get the intersection point of OC (apostrophe) and AB, and then connect C to that intersection point.

1.Flat mirrors can only multiply virtual images.

2. Extend AB to find the symmetry point D of C with respect to AB, connect OD to AB and connect E to OE and CE.

1.The answer is wrong, it should be option A, the convex lens does not explain, because the light rays of the parallel principal optical axis pass through the convex lens, and the focus is on the left of q from the refracted rays of b and b, and the focus is on the right of p from the refracted rays of a and a. So the OP should be smaller than the focal length.

2.Remember that the principle of the lens is refraction, and refraction is "at a large angle in the air", so a glass with air in the middle can actually be seen as two concave lenses that are buckled together. The concave lens has a divergent effect on the light, and the light diverges, forming a black shadow in the middle, away from the paper, the black shadow gradually becomes larger, and the bright line becomes thicker.

1: Convex lenses have the effect of converging light. From the figure, it can be seen that the rays of A and B are converged towards the optical axis. So it's a convex lens. Parallel rays are converged through the convex lens, B rays are oblique upward, the convex lens has a certain ability to gather light, and the P point must be on the right side of the focal point.

2: Because the place where the test tube is filled with water is equivalent to a convex lens, and the bubbles with the water around the periphery form a concave lens.

Thinning first and then thickening. Sunlight shines downwards from just above the tube, and the bubbles form a concave lens with the surrounding water to disperse the light to the edges. There is almost no light under the bubbles.

Light is refracted through oblique retrogression, and the bubble is angled to the surface where it meets the water.

1. Analysis: The light parallel to the main optical axis is refracted and intersects with the lens focus, and the light light away from the main optical axis is close to the lens after refraction, and the light close to the main optical axis is refracted and far away from the lens.

2 Concave, convex.

Thinning first and then thickening. Sunlight shines downwards from just above the tube, and the bubbles form a concave lens with the surrounding water to disperse the light to the edges. There is almost no light under the bubbles.

I think it's a choice, I don't know what others think.