Chapter Name: Some Natural Phenomena
Activity Name: Make your own sun-dial in Stars and the Solar System
In this activity, you will create a simple sun-dial to measure time based on the position of the sun’s shadow. The sun-dial consists of a right-angled triangle mounted vertically on a wooden board. By marking the shadows cast by the sun at different times throughout the day, you can determine the time.
- Cardboard sheet
- Rectangular wooden board
- Strips of paper
Step by Step Procedure:
- Cut a right-angled triangle (ABC) from the cardboard, ensuring that angle C of the triangle is equal to the latitude of your city or town, and angle A is 90 degrees.
- Fix the cardboard triangle vertically in the middle of the wooden board.
- Glue strips of paper along both edges of BC and the wooden board to support the triangle and make it stand erect.
- Take the board with the triangle to an open space that receives sunlight throughout the day. Ensure that the base BC of the triangle points in the north-south direction, with B pointing to the north.
- At 9 o’clock in the morning, draw a line along the shadow of side AC on the wooden board. Write the time next to the line.
- Draw lines for the shadow of side AC at one-hour intervals (using a clock to check the time) until sunset, and mark the time for each line.
- Your sun-dial is now ready to use.
- The sun-dial will show different positions of the sun’s shadow at various times of the day, allowing you to tell the time based on its markings.
- Ensure the cardboard triangle is firmly attached to the wooden board to avoid any misalignment.
- Place the sun-dial in a location that receives direct sunlight throughout the day for accurate readings.
- Make sure the base of the triangle (BC) is aligned in the north-south direction for correct time readings.
Lesson Learnt from Experiment:
This activity helps demonstrate how ancient civilizations used sundials to measure time based on the position of the sun. It also teaches about the concept of solar time and the Earth’s rotation.