Simple Kids Crafts is a video blog dedicated to reviving the old art of handicrafts for people of all ages. How do oil spills affect aquatic plants? A Miniature Solar Panel Fire Water Balloon Make Clouds in a Bottle Secret Messages Make a Rocket Make a Hovercraft Make an Anemometer Make a Sundial Make a Radio Make an Electroscope Make a Stethoscope Make a Telescope Make a Periscope Make a Camera Bending a stream of water with a comb Lighting a bulb without electricity Simple Motor Cotton Ball Rocks? Salt-Absorbing Art and Science Color Changing Glue Art Baking Soda Clay Oil Sun Catcher Grow a Pineapple Plant! Bead Bowls Wow, what an Air-Gun Funny Diver ! Water boils without fire Ice with Boiling Water Water that boils instantly Water boils in a Paper Pot Soap-driven Boat Pulse Moves Pin Pretty Garden—without Plants Picture made by Fire Magic Pictures Dancing Doll Smoke Goes Down The Dancing Coupl The Umbrella Dance Magic Butterfly Colorful
Shadow sticks or obelisks are simple sundials. If the sun rose and set at the same time and spot on the horizon every day, they would be fairly accurate clocks. However, the sun's path through the sky changes every day because the earth's axis is tilted. On earth's yearly trip around the sun the North Pole is tilted toward the sun half of the time and away from the sun the other half. This means the shadows cast by the sun change from day to day.
Sundials only measure local solar time. If a friend had a sundial 5 degrees longitude to the west of your sundial, his sundial would read a different time than yours. This is a simple calculation: the earth turns 360 degrees in about 24 hours, therefore the sun's apparent position moves 360/24 = 15 degrees each hour. So your friend's sundial would read 20 minutes different (earlier) than yours. This difference is only affected by longitude, not latitude. To standardize things, the earth was divided into 24 time zones in the 1840's, each to be one hour different from the next.
You too can make a sundial. It can be done fairly easily. Here is a very simple method for making a sundial. All you need is: A sheet of cardboard, scissors and a square wooden board.
The method of construction is described as follows.
Cut a triangular piece of cardboard in such a way that its angle at point A is equal to the latitude of the city where you are make/use the sundial. (in Delhi this angle is 28.5o and the angle B is equal to 90 (Figure below )
Erect this triangle vertically on the wooden board. To keep it in erect position fix it with the help of two paper strips on its either side. Now keep it on flat ground in such a place that is sunny all through the day. Arrange the board in such a way that the side AC of the triangular cardboard points towards the north-south direction and the point C is towards North. With the help of a watch, mark the shadow of the side AB on the wooden board after every hour starting from 9 A.M. Write the time by the side of the shadow line. Be careful that the side AC always points in the north-south directions while using this sundial.
Comments
Post a Comment