How to form a round light spot in the shade of a tree in the sun is explored. It is found that the light spot is formed by the sun through a small hole. It is also found that the image has size and which factors are related to the size of the image eleven

How to form a round light spot in the shade of a tree in the sun is explored. It is found that the light spot is formed by the sun through a small hole. It is also found that the image has size and which factors are related to the size of the image eleven

1. Ask questions:
Observe the phenomenon of sunlight passing through the shade of trees. What phenomena can you see and what questions can you ask?
(see many round light spots, where do they come from? Also see some non-circular light spots, how do they form?)
2. Guess and predict
① If the light transmitting hole is non-circular, the formed spot is non-circular;
② The size of the hole may affect the shape of the spot
Which conjecture is right?
3. Collect factual evidence
The students are divided into two or three groups to observe the image of sunlight on the screen through the holes on the paper
Let the sunlight pass through the holes of different shapes (triangle, square, diamond, trapezoid, etc.) to observe the image
Let the sunlight pass through various large holes (triangle, square, diamond, trapezoid, etc.) on the paper to observe the image
4. Draw conclusions and explain
By analyzing the collected facts, it can be concluded that the images formed by the small hole are all round, which has nothing to do with the shape of the hole. When the hole is large enough, the circle disappears, and the light spot similar to the shape of the hole is obtained
The above conclusion can be explained by the straight forward principle of light: that is, a light spot on the solar surface forms a spot on the screen through a small hole, and all the light spots form their own corresponding spot, thus forming a sun image

The sunlight passes through the gap between the leaves and forms many round spots on the ground

This is the real image of the sun formed by sunlight passing through the gap. Its shape is the shape of the sun, not the shape of the gap between the leaves‘
This is keyhole imaging

The relationship between the shape of light spot and the size and shape of light transmitting hole
1. Let the sunlight pass through the holes with different shapes (such as square, prism, triangle, etc.) on the card to observe the light spot formed on the light screen. What is the shape of the light spot?
2. Let the sunlight pass through the triangular holes of different sizes on the card to observe the light spot formed on the light screen. What is the shape of the light spot?
3. Let different shapes of luminaries (such as incandescent lamp, candle flame, etc.) observe the light spot formed on the light screen through the holes of different shapes (such as square, prism, triangle, etc.) on the card. What is the shape of the light spot?
Through the above experiments, it is concluded that: when sunlight passes through various shapes of small holes, the light spot formed is () [non-circular / circular], which is related to / irrelevant to the shape of the hole (); when the light passes through to a certain extent, the light spot with similar shape to () [transparent body / luminescent body] is obtained. Through the above exploration, Xiao Ming believes that: in the process of partial eclipse on the birthday, the, The light spot formed by sunlight passing through the gap of leaves is () [round / crescent]
Let different shapes of luminaries pass through different shapes of holes on the card to get a light spot similar to the shape of () [translucent / luminescent body]

1. Let the sunlight pass through the holes of different shapes (such as square, prism, triangle, etc.) on the card to observe the light spot formed on the light screen. What is the shape of the light spot? Circle; (that is the image of the sun). 2. Let the sunlight pass through the triangle holes of different sizes on the card to observe the light spot formed on the light screen