Determining the Gravitational Constant

The Gravitational Torsion Balance with IR Position Detector is designed to determine the Universal Gravitational Constant (G) using the Cavendish torsion balance method. The apparatus incorporates an infrared position detector for automatic measurement of the torsion balance deflection, allowing accurate data acquisition and computer-based analysis. It supports both the end-deflection and acceleration methods, providing an efficient and precise solution for advanced gravitational experiments. Manufactured by Atico Export India.

Principle

The experiment is based on the Cavendish method for determining the Universal Gravitational Constant. The gravitational attraction between masses produces a small angular deflection of the torsion balance. An infrared position detector continuously monitors this deflection by projecting infrared beams onto a concave mirror attached to the torsion pendulum. The reflected beam is detected by an array of phototransistors, enabling automatic measurement of angular displacement. The recorded data is transferred to a computer for analysis using either the end-deflection method or the acceleration method.

Objectives

• Determine the Universal Gravitational Constant (G).
• Study the gravitational attraction between masses.
• Measure the angular deflection of a torsion balance automatically.
• Analyze experimental data using computer-based software.
• Compare the end-deflection and acceleration methods.

System Components

Gravitational Torsion Balance :

• Quantity: 1

IR Position Detector :

• Quantity: 1

Optical Bench :

• Standardized Profile
• Length: 1 m
• Quantity: 1

Optics Rider :

• 60/50
• Quantity: 1

Optics Rider :

• 90/50
• Quantity: 1

Stand Rod :

• Length: 25 cm
• Diameter: 12 mm
• Quantity: 1

Automatic IR Position Detection :

• Infrared position detector enables automatic measurement of torsion balance motion.

Infrared Optical System :

• Four infrared LEDs project beams onto the concave mirror.
• Reflected beam is detected by an array of 32 phototransistors for accurate position measurement.

Computer-Based Data Acquisition :

• Experimental data is transferred directly to a computer through an RS-232 serial interface.

Data Analysis Software :

• Windows-based software provided for measurement and evaluation.

Dual Measurement Methods :

• Supports both the end-deflection method and the acceleration method.

Alternative Data Recording :

• Compatible with a Y-t recorder for data acquisition.