Simple Pendulum Physics Practical class 11 | find the effective length of second's pendulum EP 6

Introduction

This tutorial guides you through conducting a simple pendulum experiment to determine the effective length of a second's pendulum. By plotting the length versus the square of the period graph (L-T²), you will gain insights into the oscillatory motion of a pendulum, an essential concept in physics. This practical experiment is especially relevant for Class 11 physics students.

Step 1: Gather Your Apparatus

Before starting the experiment, ensure you have all the necessary materials:

• Clamp with stand
• Bob with hook (metallic spherical bob)
• Split cork
• Stop clock or stopwatch
• Vernier callipers
• Cotton thread
• Half meter scale

Practical Tip

Check that all apparatus are in good condition. Ensure the clamp can securely hold the pendulum and that the bob is heavy enough for effective oscillation.

Step 2: Set Up the Simple Pendulum

1. Attach the Bob:

   • Securely attach the metallic bob to the cotton thread.
   • Use the hook to connect the bob to the thread.

2. Fix the Setup:

   • Fix the other end of the thread to the clamp on your stand.
   • Make sure the pendulum can swing freely without any obstruction.

3. Adjust the Length:

   • Use the half meter scale to adjust the length of the pendulum. The effective length is the distance from the pivot point (where the thread is attached) to the center of the bob.

Common Pitfall

Ensure the pendulum is vertical and does not touch any surfaces during its swing to avoid inaccuracies in timing.

Step 3: Measure the Period of Oscillation

1. Displace the Pendulum:

   • Pull the pendulum to one side (no more than 15 degrees) and release it to initiate the oscillation.

2. Timing the Oscillation:

   • Use the stop clock or stopwatch to measure the time taken for a specific number of oscillations (e.g., 10 swings).
   • Divide the total time by the number of oscillations to find the average period (T).

Practical Tip

Repeat the timing process three times to ensure accuracy, and take the average of your results.

Step 4: Calculate L-T² Values

1. Square the Period:

   • For each length measured, calculate T² (the square of the period).

2. Compile Data:

   • Create a table with the effective length of the pendulum (L) and the corresponding T² values.

Example Table Format

| Length (L) | T (s) | T² (s²) | |------------|-------|---------| | 0.5 m | 1.42 | 2.0164 | | 0.6 m | 1.55 | 2.4025 | | ... | ... | ... |

Step 5: Plot the L-T² Graph

1. Graph Setup:

   • On graph paper, plot the effective length (L) on the x-axis and T² on the y-axis.

2. Draw the Line of Best Fit:

   • Analyze the data to draw a line of best fit. This line will help in determining the relationship between length and the square of the period.

Practical Application

The slope of the L-T² graph will be directly linked to the value of g (acceleration due to gravity).

Conclusion

In this experiment, you learned how to set up a simple pendulum, measure its period, and plot a graph to find the effective length of a second's pendulum. This practical exercise not only reinforces theoretical concepts in oscillatory motion but also enhances your experimental skills. As a next step, consider exploring how changing the mass of the bob or the amplitude of the swing affects the period of the pendulum.