Chapter Name: Some Natural Phenomena
Activity Name: Observing the changes in the length of shadow in Stars and the Solar System
In this experiment, students will observe and record the changes in the length of a shadow cast by a vertical stick throughout a day with clear skies. The objective is to understand how the position of the Sun affects the length of the shadow.
- A stick a little over a meter long
- A nail or peg
- A flat open ground with constant sunlight
- Clock or timekeeping device
- Table to record observations
Step by Step Procedure:
- Choose a day with clear skies, preferably between 9 AM and 4 PM.
- Select an open ground with continuous sunlight throughout the day, free from obstructions like trees or buildings that can cast shadows on the spot.
- Fix the stick vertically into the ground, ensuring exactly one meter of the stick remains above the ground. Optionally, build a fence around the stick to prevent interference.
- At 9 AM, make the first observation. Mark the point where the tip of the shadow falls on the ground using the nail or peg, and measure the length of the shadow.
- Make similar observations every half an hour until 4 PM, using a clock to note the time of each measurement.
- Record the measurements of the length of the shadow and the corresponding time in a table with two columns.
Record the length of the shadow and the time of measurement at 9:00 AM, 9:30 AM, 10:00 AM, 10:30 AM, and so on until 4:00 PM.
- Ensure a clear sky and continuous sunlight during the experiment.
- Choose a location without obstructions that may cast additional shadows on the spot.
- Secure the stick firmly in the ground to avoid movement or tilting.
- Take care not to disturb the pegs and stick during the observation period.
Lesson Learnt from Experiment:
Through this experiment, students will observe that the length of the shadow changes throughout the day due to the apparent movement of the Sun across the sky. The shadow is shortest when the Sun is at its highest position (noon) and becomes longer in the morning and afternoon. This activity helps in understanding the apparent motion of the Sun and its relation to the time of day.