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Determination of the Gravitational Constant Manufacturer,Supplier and Exporter in India

Product Code : EL-TWL-9166
Jlab Export is a leading Determination of the Gravitational Constant Manufacturer,and suppliers in India

This apparatus measures the gravitational constant G with a torsion balance of the Cavendish type. A light bar with two small lead spheres hangs from a 25 µm tungsten wire, and two 1 kg lead spheres pull it round. A capacitive differential sensor reads the tiny rotation and passes it to a computer, so G can be found within one lesson.

Specifications

Method	Torsion pendulum read by a capacitive differential sensor
Torsion wire	Tungsten, 25 µm
Small lead spheres	Two, 15 g, on a light bar
Large lead spheres	Two, 1 kg
Angular resolution	25 microradians
Period of oscillation	2–4 min
Sampling rate	0.5, 1, 2, 5 or 10 samples/s
Gravitational attraction	Below 10^-9 N
Data output	Recorded on a computer, exportable to a spreadsheet
Size and weight	190 x 180 x 200 mm, 5 kg
Minimum order quantity	1 unit
Dispatch time	Usually 7–10 working days
Manufacturer	JLab (Jain Laboratory Instruments Pvt Ltd), Ambala, India

Experiments with the Torsion Balance

In the main experiment, students let the pendulum settle, then swing the two large spheres to the opposite side of the small ones. The balance turns towards a new rest position and oscillates about it with a period of 2–4 min. The computer record shows both rest positions and the period. G then follows from the shift between the rest positions, the torsion period, and the masses and spacing of the spheres.

Because the swing is so slow, a Digital Stopwatch is enough to cross-check the period by eye. For a class demonstration, the light-pointer method can replace the sensor, with a Laser Light as the source. The spot moves along the wall, and a Measuring Tape gives the distance needed to turn its shift into an angle.

Why the Set-Up Needs Care

The pull between the spheres is below 10^-9 N, so air currents, a knock on the bench or a change in room temperature can disturb the reading. The capacitive sensor suppresses much of the noise and vibration in the signal. Even so, stand the apparatus on a firm bench away from doors and fans, and move the large spheres gently.

Frequently Asked Questions

How long does one measurement of G take?
One determination fits into a single lesson. The pendulum swings with a period of 2–4 min, so a few oscillations about each rest position are enough to locate it. The result can come within 10% of the accepted value.

What sampling rates can the sensor record at?
It records at 0.5, 1, 2, 5 or 10 samples per second. A slow rate is enough for the long swing of the pendulum, and a faster rate shows the start of the motion in more detail. The data can be exported to a spreadsheet.

Why is such a thin tungsten wire used?
A thin wire twists easily, so the very small gravitational torque turns the bar far enough to measure. Tungsten is strong for its size, so a 25 µm wire can still carry the bar with its two 15 g spheres.

Can G be measured without a computer?
The sensor output is recorded on a computer. Without one, the motion can be shown with a light pointer and read off a scale on the wall, and the period timed by hand. This suits a demonstration more than a full measurement.