Article: This experiment will allow you to create a light pinhole, which will show you how light travels in a straight line by filtering it through a hole. To create a light pinhole, you will need the following supplies:  Three index cards. A piece of modeling clay or sticky tack. You can also use double sided tape. A flashlight or a laser pointer. A hole puncher. A ruler. To do this without any excessive measuring, use the ruler to draw two diagonal lines on an index card that connect the opposite corners of the card. Repeat this for the other two cards. Take the hole puncher and punch a hole at the center of the card where the two lines intersect. Do this for the other two cards. The cards need to stand vertically, at equal distance from each other, and in a straight line for this experiment to work.  Form a stand for the cards using the clay so the cards are straight and upright. Use the ruler to ensure the cards are two to five inches from each other. You can also use double sided tape to attach the cards to a surface in a vertical position. Do not cover or obstruct the hole in the center of the cards with modeling clay or tape. Hold the flashlight in your hand so it hits the center of the hole in the first card. Turn on the flashlight or the laser pointer. Note that the light can be seen through all the holes. You should be able to see the light go through all the holes and land on a wall or surface beyond the last index card. You will note that the light does not travel beyond the card. This illustrates that light will travel in a straight line when it hits a non reflective material like the index card.
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Gather your materials. Punch a hole in the center of the index cards. Use the modeling clay to stand up the cards. Position the flashlight or the laser pointer at one end of the row of cards. Move the flashlight or laser pointer so it does not hit the center of the first card.