光的知识（Light knowledge）.docVIP

光的知识（Light knowledge） I. instrument The size of the experiment error is closely related to the size of the pinhole and the thickness of the pencil line. Good paper, needle, pen and brick should be used. Optical paper should avoid moving in operation. You can also find some paper folded into three or four layers of thick paper, slightly larger than the area of the picture, make 4 pieces of picture respectively through this paper, and then pressed on the four corners of the recording optical paper, this paper is not easy to slide, and pin easy to remove. To determine the optical pathway pin should be inserted straight, observation should be focused look at the nail feet in a line is very small. The needle pin cap, directly pressed by hand, finger pain, between the needle cap and pin pad of paper fingers or other objects. Pay attention to the protection of transparent glass brick, finger as far as possible not to touch the glass brick. Painting glass brick boundary, it is best not to directly around the pencil glass brick paintings, as shown in Figure 1 in the paper along a moment variable scale draw a straight line AA , then put the glass brick, make an interface with a straight line aa` alignment glass brick, with the scale to another interface of glass bricks, as shown in Figure 2. Carefully remove the glass brick, the ruler draw second interface BB glass brick, as shown in Figure 3 Practice shows that even the pencil pinhole is accurate or not, the thickness of the line has a great influence on the experimental results. The pencil should be used as the hardness slightly larger, pencil with a knife after roughing, put on the cement board carefully sharpened, so draw Pin refraction method to measure the glass rate is the traditional method of secondary physics teaching, because a pin has a certain thickness, in not too long a distance within the thickness can not be ignored, and the pin due to board or desktop is hard, it is difficult to guarantee the needle and the