Demonstration Device of an Alarm from a Clock Under a Bell Manufacturer,Supplier and Exporter in India

Demonstration Device of an Alarm from a Clock Under a Bell (Product Code: SCL-345/031) is a bell-jar vacuum apparatus used to prove that sound needs a medium to travel, in school physics lessons on sound. An electric bell rings inside a glass cage while a vacuum pump draws out the air, so the class hears the ringing fade even though the bell can still be seen working. It is made by Jain Scientific Equipments Pvt Ltd (ScienceLab), an OEM manufacturer, at its own factory in Ambala, India.

Key Details

What Is the Bell Under a Glass Jar Demonstration Used For?

This is the classic “alarm clock under a bell jar” experiment, built here around an electric bell. The bell is connected through the rubber plug to the power source outside, switched on so everyone hears it clearly, and then the vacuum pump steadily removes air from the glass cage. As the air thins the sound grows faint, yet the striker keeps moving; letting air back in brings the ringing back.

The result shows that sound is a mechanical wave that needs particles to carry it, unlike light, which still reaches the students’ eyes through the evacuated jar. It is a staple of physics lab equipment for secondary classes studying sound. Check the glass for chips before each use, keep a safety screen or a clear distance while the jar is under vacuum, and let air in slowly before lifting the cage.

What to Specify When Ordering

• The number of demonstration sets — usually one per physics laboratory.
• The mains supply at your site, so the power source and vacuum pump arrangement can be confirmed — ask us.
• Whether a spare glass cage or rubber plug should be quoted for breakage cover.

OEM Manufacturer

Jain Scientific Equipments Private Limited, trading as ScienceLab, is the OEM (original equipment manufacturer) that assembles this bell-in-vacuum demonstration at its own licensed factory at Saha, Ambala, Haryana, India. The company is a registered MSME manufacturer (Udyam UDYAM-HR-01-0003714), and international consignments move under its Importer-Exporter Code AAECJ8618A issued by the DGFT. Schools, dealers and importers get quotations and after-sales answers from the maker itself; see the ScienceLab profile.

Related Laboratory Equipment

Related items for sound and vacuum demonstrations:

• Bell In Glass Jar and Base — an alternative bell-jar arrangement for the same experiment.
• Vacuum Pump with Pressure Gauge — lets students relate the fading sound to a falling pressure reading.
• Vacuum Pump, Hand — a manual pump for other air-pressure experiments.
• Tuning Fork on Resonance Box — follows on by showing how sound travels through air and solids.

The Laboratory Equipment category lists more demonstration apparatus.

Frequently Asked Questions

What does the Demonstration Device of an Alarm from a Clock Under a Bell show?
The Demonstration Device of an Alarm from a Clock Under a Bell shows that sound cannot travel through a vacuum. As air is pumped out of the glass cage, the electric bell becomes harder to hear while it can still be seen ringing.

What is included with this bell-in-vacuum device?
The Demonstration Device of an Alarm from a Clock Under a Bell includes a glass cage, an electric bell, a rubber plug with two sockets, a glass tube, an electric power source, a black 1 m conductor, a red 1 m connecting wire and a vacuum pump.

Why does a little sound remain after pumping?
With the Demonstration Device of an Alarm from a Clock Under a Bell, a faint sound may remain because a classroom pump cannot remove every air particle, and some vibration travels through the plug and leads. The sharp drop in loudness is the key observation.

Who manufactures the Demonstration Device of an Alarm from a Clock Under a Bell?
The Demonstration Device of an Alarm from a Clock Under a Bell is manufactured by Jain Scientific Equipments Pvt Ltd (ScienceLab), the OEM, at its own factory at Saha, Ambala, Haryana, India, and supplied direct to schools, dealers and importers.

How should the glass cage be handled safely?
Inspect the glass cage of the Demonstration Device of an Alarm from a Clock Under a Bell for cracks before every use, keep students at a safe distance while it is under vacuum, and release the vacuum slowly before removing the cage.

How can a school get a quotation for this device?
To get a quotation for the Demonstration Device of an Alarm from a Clock Under a Bell, send the number of sets, your mains supply details and the delivery location through the contact page. ScienceLab supplies India and international markets.

Request a Quote

Request a price for the Demonstration Device of an Alarm from a Clock Under a Bell on the contact page or add it to your enquiry cart. The quotation is issued directly by the manufacturer, with no trading intermediary in between.

Last updated: 24 September 2026