Ballistic Galvanometer
Product Code : EL-LM-10391
Quick answer: The Ballistic Galvanometer is a moving-coil galvanometer with a long 12 s period, used to measure small quantities of charge and very low currents, for example when comparing capacitances or measuring magnetic flux with a search coil. It comes in 100 ohm and 500 ohm versions with a charge sensitivity of 300 or 600 mm/µC. Lab Exports manufactures it in Delhi for colleges and universities.
Specifications
| Parameter | Value |
|---|---|
| Coil resistance | 100 ohm or 500 ohm (two variants) |
| Time period | 12 s (both variants) |
| Charge sensitivity | 300 mm/µC (100 ohm); 600 mm/µC (500 ohm) |
| Current sensitivity | 1000 mm/µA (100 ohm); 1400 mm/µA (500 ohm) |
| Critical damping resistance | 2000 ohm (100 ohm); 3500 ohm (500 ohm) |
| Movement | Mirror-suspended coil on a long upper suspension and a lower spring, both of a special alloy |
| Levelling | Levelling screws for balancing the coil |
| Housing | Bakelite case |
How the ballistic galvanometer experiment is done
A ballistic galvanometer measures a quantity of charge that passes in a short pulse. Because its period is long, the whole charge Q passes through the coil before the coil has moved appreciably; the coil then swings out, and its first throw theta is proportional to the charge, Q = K x theta, where K is the ballistic constant of the instrument.
- Level the galvanometer with its levelling screws so the coil hangs freely in the magnet gap.
- Read the mirror deflection with a lamp and scale placed in front of the instrument.
- Charge a capacitor from a steady source and discharge it through the galvanometer; note the first throw.
- Repeat with a second capacitor charged from the same source.
- Short-circuit the coil through a damping key between readings so it comes to rest quickly.
For two capacitors charged to the same voltage, C1/C2 = theta1/theta2. The same method is used for measuring high resistance by leakage and for finding magnetic flux with a search coil.
Key features
- Two coil-resistance variants, 100 ohm and 500 ohm, both with a 12 s period.
- Charge sensitivity of 300 or 600 mm/µC for small pulses of charge.
- Current sensitivity of 1000 or 1400 mm/µA for very low steady currents.
- Mirror-suspended coil on a special-alloy suspension with a lower spring.
- Levelling screws for balancing the coil and a Bakelite case protecting the movement.
Documentation and supply
Installation instructions and a manual are supplied with the galvanometer. Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the Ballistic Galvanometer at its works in Laxmi Nagar, Delhi, and supplies it to 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.
Related Lab Meters products
- Galvanometer EDSPOT (EL-LM-10390)
- Basic Meter (EL-LM-10392)
- Demonstration Meter Interscale (EL-LM-10389)
- Tangent Galvanometer (EL-LM-10393)
- Demonstration Meter Vertical (EL-LM-10388)
- Ohms Law Apparatus (EL-LM-10394)
The full range is in the Lab Meters section of the Physics Lab range.
Frequently asked questions
Why does a ballistic galvanometer have a long time period?
With a 12 s period the whole charge passes through the coil before it moves appreciably, so the first throw is proportional to the charge.
Which variant of the ballistic galvanometer should be ordered?
The 100 ohm version gives 300 mm/µC and 1000 mm/µA with a 2000 ohm critical damping resistance; the 500 ohm version gives 600 mm/µC and 1400 mm/µA with 3500 ohm. Name the variant in the enquiry.
What is the price of the Ballistic Galvanometer?
Prices are not published on the website. Add the Ballistic Galvanometer to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-LM-10391 and the quantity, to receive a quotation.
Does Lab Exports manufacture the Ballistic Galvanometer?
Yes. Lab Exports manufactures the Ballistic Galvanometer at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-LM-10391.
Request a quote
Email [email protected] with the house code EL-LM-10391 and the quantity, or add the Ballistic Galvanometer to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
