Bell Experiment Apparatus

Product Code : EL-POM-10364

Specifications

How the bell jar experiment is done

Sound is a mechanical wave and needs a material medium, such as air, to carry it. While the jar is full of air the bell is heard clearly through the glass. As the air is pumped out, fewer molecules are left to pass the vibrations on, and the ringing grows faint even though the striker can still be seen moving.

1. Seat the 2 litre bell jar on the plate of the air pump so that the rim seals.
2. Connect a 3 to 6 V battery or transformer to the binding posts on the rubber stopper and switch the bell on.
3. Listen to the bell with the jar full of air, then begin pumping the air out.
4. Note how the sound fades as the pressure falls, while the bell is still seen working.
5. Open the air inlet on the pump plate and listen as the sound returns.

Students conclude that sound needs a medium to travel, while light still crosses the evacuated jar, which is why the bell stays visible. A school pump never removes every trace of air, and some vibration also passes through the stopper, so a faint sound usually remains; this makes a good point for class discussion.

Key features

• 2 litre bell jar that gives a clear view of the bell throughout the experiment
• Rubber stopper with binding posts and connectors that carry the supply into the jar
• Electric bell suspended from the stopper, clear of the glass walls
• Low 3 to 6 V operation from a battery or a transformer
• Designed to be used with the Lab Exports air pump with aluminium plate

Documentation and supply

Installation instructions and a manual are supplied with the apparatus. Most Lab Exports products carry a one-year manufacturer warranty.

Lab Exports manufactures the bell experiment apparatus at its works in Laxmi Nagar, Delhi, and supplies it to schools, colleges and universities in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.

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• Magdeburg Hemispheres (EL-POM-10366)
• Metal Cubes (EL-POM-10361)
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The full range is in the Properties of Matter section of the Physics Lab range.

Frequently asked questions

What does the bell experiment apparatus demonstrate?

It demonstrates that sound needs a medium to travel: the bell becomes faint as the air is pumped out of the jar, although it can still be seen ringing.

What voltage does the bell need?

The electric bell works on 3 to 6 volts, supplied from a battery or a transformer.

Is a vacuum pump included?

No. The Air Pump (Vacuum Pump with Aluminium Plate) is needed to evacuate the jar and is sold separately.

What is the price of the bell experiment apparatus?

Prices are not published on the website. Add the bell experiment apparatus to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-POM-10364 and the quantity, to receive a quotation.

Does Lab Exports manufacture the bell experiment apparatus?

Yes. Lab Exports manufactures the bell experiment apparatus at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-POM-10364.

Request a quote

Email [email protected] with the house code EL-POM-10364 and the quantity, or add the bell experiment apparatus to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.