CN2507096Y

CN2507096Y - Double bridge demonstrator

Info

Publication number: CN2507096Y
Application number: CN 01273939
Authority: CN
Inventors: 骆乃光
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-10
Filing date: 2001-11-10
Publication date: 2002-08-21
Anticipated expiration: 2011-11-10

Abstract

The utility model relates to a double bridge demonstrator. Two long wire-wound resistors are fixed on the base board in parallel, and a rule with the same length is equipped in the middle; both wire-wound resistors are equipped with a contact, and both contacts slide synchronically; the proportional relation of both long wire-wound resistors as double bridge ratio arms can be measured from the rule, and both sliding contacts are connected with a galvanometer to carry out balance display. The base board is provided with two sets of four terminated line columns, wherein four electric potential ends are connected with two wire-wound resistors end-to-end, and four electric current ends are respectively connected with the power, the measuring resistance and the measured small resistor. The double bridge demonstrator can effectively decrease the error caused by the lead wire when measuring the small resistor, and the students can carry out proportion conversion intuitively.

Description

The doube bridge demonstrator

The utility model relates to the demonstration instrument of in colleges and universities' Experiments of Electromagnetism small resistor being measured.-

Still there are not at present the enough double bridge principles of energy to carry out the demonstration instrument of small resistance measurement, therefore, say when double bridge is measured the small resistor principle, can only on blackboard, draw circuit diagram with reference to box double bridge and analyze and calculate, perhaps substitute two ratio arms with four resistance boxes.

The purpose of this utility model provides a kind of double bridge apparatus for demonstrating, allows the student does it yourself to operate, the selection percentage relation, carries out the experiment of small resistance measurement.

It is that φ 1～3mm metal wire is a baseline that the utility model is achieved in that with two diameters, above closely around the resistance wire thinner than baseline, from the beginning around to tail, and fix with glue.Require to insulate between the every circle of thin resistance wire, for this reason, available polyester enamel-cover manganese-copper filament or enamel-cover constantan wire, an also available exposed resistance wire and an enameled wire are side by side on baseline.Resistance length after the coiling is advisable to 150cm at 33cm, and resistance value is between 100 Ω-10K Ω.Require that resistance after two coilings is isometric to wait resistance.

The resistance wire after these the two isometric coilings such as resistance such as grade, secured in parallel is on base plate, between two resistance, be provided with a same long rule on the base plate with resistance wire, a slider respectively is equipped with in two resistance wire upper ends, two contact insulation and slips synchronously each other all have exit to be connected with galvanometer.Light is scraped with the breaking saw blade sheet in the resistance wire surface that contacts with slider, and is good to keep in touch.

The head and the tail two ends of two resistance wires respectively are connected on four potential end binding posts of base plate, and four current terminal binding posts are established in the both sides on base plate, just finish the manufacturing of this instrument.

Doube bridge demonstrator of the present utility model, proportionate relationship show directly that on ruler the student learns more directly perceived.

Below in conjunction with drawings and Examples the utility model is further specified.

Accompanying drawing is the utility model doube bridge illustrative circuitry figure.

Among the figure, 1. 8. 4 fixed supports of eight binding posts of two 7.A, B, C, D, E, F, G, H of one of 2 4. rules, 5. sliders of long resistance wire 6. sliders after 3. coilings of one of long resistance wire after base plate 2. coilings

External connection battery 12 is connected on current terminal A, B 2 points in the accompanying drawing, and external standard resistance box 10 adopts four termination collimation methods, and E, H are current terminal, and F, G are potential end, and 11 two signal input lines of external galvanometer are connected on sliding contact 5 and 6 respectively.To tested small resistor 9 also by four termination collimation methods, two current potential termination B and C, electric current termination A and D connect D and E with heavy gauge wire, have just finished a complete doube bridge circuit.When slider 5 and 6 slides into certain some galvanometer 11 balance synchronously, just can extrapolate the proportionate relationship of standard resistance box and tested small resistor from the length ratio relation of rule 4.

The utility model specific embodiment, getting baseline is φ 2.6 enamel covered wires, and resistance wire adopts the enamel-cover manganese-copper filament of φ 0.16, and length is 80cm after the coiling, about 1000 Ω of resistance after the every coiling.Four fixed supports 8 are even be fixed on the edge of long resistance, and when bumping against with slider 5 and 6, still there is the distance of 2cm sliding contact and long resistance contact position from end points, and this section resistance is about 25 Ω.The lead-in wire of four terminated lines generally is no more than 25 * 10 ^-3Ω that is to say, present embodiment is under extreme case, and the lead-in wire error is no more than 0.001.

Claims

1. doube bridge demonstrator, it is characterized in that with two equally thick metal wires be baseline, above thereon with equally thin metallic resistance filament winding, make two equally long long wire-wound resistor (2) and (3), long wire-wound resistor secured in parallel is on base plate (1), and two respectively connects two potential ends, respectively there are two current terminal contacts the both sides, a rule (4) is arranged between two long wire-wound resistors, a sliding contact (5) and (6) are respectively arranged on the long wire-wound resistor, they slide synchronously.

2. doube bridge demonstrator according to claim 1 is the enamel manganin that adopts φ 0.16, forms two each long 80cm of elongated resistance on diameter phi 2.6 enameled wires.