CN2031553U

CN2031553U - Demonstrating device showing metal conductor resistivity changed with the temp. variation

Info

Publication number: CN2031553U
Application number: CN 88205110
Authority: CN
Inventors: 张春宇
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-29
Filing date: 1988-04-29
Publication date: 1989-01-25

Abstract

The utility model relates to a demonstrating device, belonging to the class of educational apparatus. The demonstrating device can demonstrate qualitatively the phenomenon that the metal conductor resistance increases with the elevation of temperature and reduces with the reduction of temperature, and the qualitatively can be used for doing demonstrating experiment in physical teaching of secondary school. The demonstrating device is composed of two small bulbs which are connected in parallel, connected with metal tungsten filaments in series and then connected to the direct current power supply of 6 volt. After the electric circuit is switched on and stable, when blowing gas towards the tungsten filaments with mouth or a small fan, the temperature is reduced. So the luminosity of the small bulb is enhanced obviously indicating that the resistance of the tungsten filaments is reduced. When blowing gas is stopped, the temperature of the tungsten filament rises back because the dissipating heat rapidity slows down, and the luminosity of the small bulb is weakened indicating that the resistance of the tungsten filaments is increased.

Description

Demonstrating device showing metal conductor resistivity changed with the temp. variation

The utility model is a kind ofly can demonstrate the temperature variant physics educational apparatus of metallic conductor resistivity.

In the physics teaching in secondary school at present, when telling about the qualitative relationships of metallic conductor resistivity and temperature, there is complex structure in demonstration instrument or heats shortcomings such as using inconvenience with naked light to metallic conductor.

The purpose of this utility model is that design is a kind of simple in structure, the temperature variant physics educational apparatus of resistivity of the qualitative demonstration metallic conductor of energy easy to use.

Circuit of the present utility model as shown in Figure 1, two miniature bulb L ₁L ₂After the parallel connection, connect with metal tungsten wire R again, be connected on 6 volts of direct supplys by switch then and form.Circuit is connected, and tungsten filament is rubescent slightly state because of heating effect of current is heated to.After treating that bulb brightness is stable, blow facing to tungsten filament with mouth or small fan, the heat that air-flow has been taken away the tungsten filament generation reduces the tungsten filament temperature, at this moment, two bulbs brighten simultaneously, show that the strength of current by bulb increases, this obviously is because the resistance of tungsten filament reduces caused, and the resistance R=P of tungsten filament (L)/(S), because the length L of tungsten filament, cross-sectional area S does not all change, so it can only be because of due to its resistivity reduces that the resistance of tungsten filament reduces, as seen, when temperature reduced, the resistivity of metallic conductor reduced.

When stopping to blow, the tungsten filament radiating rate temperature that slows down raises, and this moment, two bulb brightness weakened simultaneously, and this can only be that as seen, the resistivity of metallic conductor increased with the temperature rising due to the resistivity of tungsten filament increased.

The utility model is simple in structure, and cost of manufacture is low, and the demonstration effect is obvious, and rich interesting.

Embodiment among the available Fig. 2 of structure of the present utility model is illustrated (backplan that Fig. 3 is Fig. 2).

Wherein: (1) is the lamp socket overcoat, (2) be that tungsten filament socket (3) is a shell, (4) be nameplate, (5) be switch " canoe type switch ", (6) be miniature bulb " 2.5 volts, 0.3 pocket lamp bulb of pacifying ", (7) be tungsten filament " 0.04 millimeter of diameter; long 7 centimetres; coiled ", (8) are glass shell, and (9) are the tungsten filament holder, (10) be that screw lamp holder " supporting with miniature bulb " (11) is a little copper sheathing " supporting with pin ", (12) be the anode contact chip, (13) are the battery cathode stage clip, and (14) are base plate.

Lamp socket overcoat (1) and tungsten filament socket (2) are positioned at the back upper place projection of shell (3), connect together with shell, with opaque plastics compacting, one-shot forming.Outer casing underpart is a battery case, can divide two to arrange No. 1 battery of 4 joints of packing into, and nameplate (4) is affixed on the shell upper left front, and switch (5) is fixed in the right of shell back upper place projection.Two miniature bulbs (6) are screwed on the interior screw lamp holder (10) of lamp socket overcoat, the two ends of tungsten filament (7) are connected on two copper pins on the tungsten filament holder (9) with copper wire, in order to prevent that long-term storage center tap place from causing loose contact because of oxidation, tungsten filament (7) is sealed in the evacuated glass shell (8), two jacks are arranged on the tungsten filament socket (2), two little copper sheathings (11) wherein are housed respectively.Anode contact chip (12) is made by copper sheet.Battery cathode stage clip (13) is made them by elastic copper sheet and all is fixed in corresponding site in the shell by the mode that snaps in corresponding slot.Connect by circuit diagram 1 with lead between each part and see Fig. 3.After battery installs, cover base plate (14) and base plate is fixed on the shell with screw.

Before the demonstration, should with towel the tungsten filament holder be wrapped earlier, break glass shell gently into pieces, tungsten filament is come out, be inserted in then on the tungsten filament socket, can demonstrate.

Claims

1, the qualitative demonstration metallic conductor of a kind of energy resistivity varies with temperature and the physics teaching demonstration instrument that changes, and by shell (3), miniature bulb (6) tungsten filament (7) switch (5) is formed (see figure 2).It is characterized in that: miniature bulb (6) is parallel with one another, and by tungsten filament socket (2), tungsten filament holder (9) is connected with tungsten filament (7) switch (5).

2, demonstration instrument as claimed in claim 1 is characterized in that: tungsten filament (7) is connected on two pins on the tungsten filament holder (9) with copper wire, tungsten filament (7) coiled.