Portable Wheatstone Bridge
Product Code : SCL-EAE-11297
Quick answer: The Portable Wheatstone Bridge measures DC resistance by the null-balance method. The unknown resistor forms one arm of a four-arm bridge; decade and ratio controls are adjusted until the built-in centre-zero galvanometer reads zero, and the unknown value is calculated from the settings. Manganin coils keep the known arms stable. Lab Exports manufactures it in Delhi for schools, colleges and universities.
Specifications
| Parameter | Detail |
|---|---|
| Measurement principle | Four-arm Wheatstone bridge, null-balance method |
| Measurement type | DC resistance |
| Resistance coils | Manganin wire windings |
| Balance indicator | Integrated centre-zero moving-coil galvanometer |
| Resistance selection | Decade controls and ratio selection arrangement |
| Operating keys | Separate battery and galvanometer keys |
| Housing | Portable protective enclosure |
Measuring range, ratio steps and accuracy are not listed on this page; ask for them with the quotation.
How the Wheatstone bridge experiment is done
A Wheatstone bridge has four resistances P, Q, R and S joined in a loop, with a cell across one diagonal and a galvanometer across the other. When no current flows through the galvanometer the bridge is balanced and P/Q = R/S, so the unknown S = R x Q/P. Because the reading is taken at zero deflection, the result depends only on the known resistances, not on the calibration of the galvanometer.
In this portable bridge the ratio arms are set with the ratio selector and the known arm with the decade controls. The coils are wound from manganin, whose very small temperature coefficient keeps the known values steady during a measurement.
- Place the instrument on a stable, dry bench and connect the unknown resistor to its terminals.
- Choose a ratio setting and a starting value on the decade controls.
- Press the battery key first, then tap the galvanometer key and note the direction of deflection.
- Adjust the decades until the galvanometer shows no deflection, changing the ratio if balance cannot be reached.
- Calculate the unknown resistance from the ratio and decade settings.
Key features
- Null-balance measurement of DC resistance
- Manganin resistance coils with a low temperature coefficient
- Integrated centre-zero moving-coil galvanometer shows the direction of imbalance
- Decade controls and ratio selection for systematic balancing
- Separate battery and galvanometer keys for controlled energising
- Self-contained in a portable protective enclosure
Documentation and supply
Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the portable Wheatstone bridge 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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The full range is in the Electrical and Electronics section of the Physics Lab range.
Frequently asked questions
What is the balance condition of a Wheatstone bridge?
At balance no current flows through the galvanometer and P/Q = R/S. The unknown resistance is then found from the ratio setting and the value on the decade controls.
Why is the battery key pressed before the galvanometer key?
Closing the battery circuit first lets the currents settle before the galvanometer is connected, which protects it from a sudden deflection.
What is included with the portable Wheatstone bridge?
The bridge panel assembly with its manganin resistance network, centre-zero galvanometer and battery and galvanometer keys, housed in a portable protective enclosure.
What is the price of the portable Wheatstone bridge?
Prices are not published on the website. Add the portable Wheatstone bridge to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code SCL-EAE-11297 and the quantity, to receive a quotation.
Does Lab Exports manufacture the portable Wheatstone bridge?
Yes. Lab Exports manufactures the portable Wheatstone bridge at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code SCL-EAE-11297.
Request a quote
Email [email protected] with the house code SCL-EAE-11297 and the quantity, or add the portable Wheatstone bridge to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
