Practice of convex lens imaging law

1, the center of convex lens has _ _ _ _ _ _ effect on light than the edge; The center of concave lens has _ _ _ _ _ _ _ effect on light than the edge.

2. The calibration part of the commonly used thermometer is a triangular body with a cross section as shown on the right and an arc front, so that the extremely fine mercury column in the thermometer can be clearly seen to facilitate reading. This is because the function of curved glass is equivalent to _ _ _ _, so that we can see the image of mercury column.

3. In the experiment of studying convex lens imaging, when the candle flame is 6 cm away from the convex lens, an enlarged image can be formed on the light screen. When the candle moves away from the lens 12 cm, adjust the light screen, and _ _ _ _ _ (fill in "can" and "can't") to get a clear image on the light screen. If you can get an image, then _.

4. When the lighted candle gradually moves to the lens from the place with twice the focal length, the real image of _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ can be observed on the light screen first, and _ _ _ _ _ _ _ _ _ _ _ can be observed when the candle moves from the convex lens to twice the focal length.

5. The dividing point between the enlarged real image and the reduced real image of the convex lens is _ _ _ _ _ _ _ _; The dividing point between the real image and the virtual image of the convex lens is _ _ _ _ _ _ _ _.

6. Some students took a convex lens with a focal length of 15 cm. If you want to observe tiny objects, you should put them under the convex lens within the range of _ _ _ _ _ _. At this time, a convex lens can be used to enlarge the image.

Move a little (fill in "up" or "down"); If you want to use it to get a magnified real image, the distance from the object to the convex lens should be in the range of _ _ _ _ _ _ _ _ _, and the position of the image at this time is in the range of _ _ _ _ _ _ _ _ _ _ _ _; If you want to use it to get a reduced real image, the distance from the object to the convex lens should be _ _ _ _ _ _ _, and the position of the image at this time is within the range of _ _ _ _ _ _ _ _.

7. Teenagers with myopia should wear their eyes for vision correction; If middle-aged and elderly people suffer from hyperopia, they should wear glasses made of it to correct it. The "degree" of reading glasses is equal to the reciprocal of its focal length (in m) multiplied by 100. If a classmate measures that the focal length of the reading glasses worn by his grandmother is 25cm, the degree of the glasses is the degree.

8. When an object approaches twice the focal length of the convex lens from a distance, the image will be filled with "bigger", "smaller" and "unchanged", and the distance between the object and the image will be filled with "bigger", "smaller" and "unchanged".