Why can't everyone see the candlelight after opening a small hole in the paper, and where can students see the light when sitting?

Small hole imaging. When a wooden board with a small hole is blocked between the screen and the object, the reflection of the object will be formed on the screen, which is called pinhole imaging. Move the midplane back and forth, and the image size will change accordingly. This phenomenon reflects the nature of light propagation along a straight line. The linear propagation of light has been widely used in ancient astronomical calendars in China, and scales and sundials have been made to measure the length and orientation of the sun's shadow to determine the time, winter solstice and summer solstice. Install peepholes on astronomical instruments to observe the sky and measure the positions of stars.

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