Portable Wheatstone Bridge
Product Code : SCL-EAE-11193
Quick answer: The Portable Wheatstone Bridge is a self-contained instrument for measuring an unknown DC resistance by the null method. Students set its decade arms until the built-in centre-zero galvanometer reads zero, then calculate the resistance from the arm values. It has manganin coils and separate battery and galvanometer keys in a portable case. Lab Exports manufactures it in Delhi for schools, colleges and universities.
Specifications
| Component | Specification |
|---|---|
| Measurement | Unknown DC resistance (medium values) by the null method |
| Resistance coils | Manganin wire windings |
| Arms | Four decade switch arms on one top panel |
| Null indicator | Built-in moving-coil centre-zero galvanometer with mirror scale |
| Keys | Separate battery and galvanometer tapping keys |
| Enclosure | Portable box with protective handle and latching cover |
The measuring range is not listed on this page; email [email protected] for the range of the current model.
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 resistance S = R x Q/P. Manganin coils are used because their resistance hardly changes with room temperature, which keeps the balance point steady.
- Connect the unknown resistor to the terminals provided for it.
- Choose a ratio on the ratio arms that suits the expected value.
- Press the battery key first and then the galvanometer key, and note the direction of deflection.
- Turn the decade dials of the rheostat arm until the galvanometer shows no deflection.
- Read the dial setting, apply the ratio to get the unknown resistance, and release the keys in reverse order.
Beyond the standard practical, the bridge is used to check working resistors against a stable standard and to trace low-resistance faults and open connections in wiring.
Key features
- Manganin resistance coils with low temperature drift
- Four decade switch arms laid out on one top panel
- Built-in centre-zero galvanometer with mirror scale for a clear null point
- Separate battery and galvanometer tapping keys that protect the galvanometer from surges
- Self-contained, so no external galvanometer or resistance box is needed
- Portable case with carrying handle and latching cover
Documentation and supply
A student experiment manual and a calibration instruction sheet are supplied with the bridge. 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 does a portable Wheatstone bridge measure?
It measures an unknown DC resistance by balancing it against known manganin resistances until the built-in galvanometer reads zero. It is used in resistance measurement practicals and for checking resistors against a standard.
Why is the battery key pressed before the galvanometer key?
Closing the cell circuit first lets the currents settle before the galvanometer is connected, so the galvanometer is not jolted by a surge. The keys are released in the reverse order.
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-11193 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-11193.
Request a quote
Email [email protected] with the house code SCL-EAE-11193 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.
