CN201237849Y

CN201237849Y - Joule law demonstrator

Info

Publication number: CN201237849Y
Application number: CNU2008201044651U
Authority: CN
Inventors: 黄绍端
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-12
Filing date: 2008-08-12
Publication date: 2009-05-13
Anticipated expiration: 2018-08-12

Abstract

The utility model discloses a demonstrator of Joule law, which comprises a demonstration board, a power source, resistors and an ammeter, and also comprises three test tubes fixed on the demonstration board with an interval, wherein, each test tube is provided with a resistor with different resistance values and is filled with liquid alcohol; the upper mouth of each test tube is provided with a sealed tube plug, and the two ends of the resistor in the test tube pass through a lead seal and out of the tube plug seal; a transparent duct is arranged on the tube plug of each test tube to communicate the empty test tube with the cavity of the test tube; the duct is drawn upward to vertically cross the horizontal graduation mark on the demonstration board. In the structure of the demonstrator of Joule law, the power source, a switch, the resistors and the ammeter are connected to form a loop. The electric current flows through the resistors of the test tubes to produce heat, and the alcohol expanded by heat ascends in the duct. The relationship between the height and rate of the ascending alcohol, the magnitude and the resistance value of the current through the resistors is displayed clearly on the demonstration board. The utility model is applicable to the demonstration of experiments in schools as to the factors relevant to the amount of heat discharged by the electrified conductors.

Description

The Joule law demonstration device

Technical field

The utility model relates to a kind of teaching aid, especially the electrical conductor liberated heat lecture experiment apparatus relevant with which factor.

Background technology

In the physics lesson of middle school, the electrical conductor liberated heat lecture experiment relevant with which factor arranged, typical lecture experiment is the Joule law demonstration, teach this experiment that makes two bites at a cherry in edition teaching material the people, experiment disperses, and waste class hour, is unfavorable for observation of students, comparison and study.

Summary of the invention

The purpose of this utility model provides that a kind of picture is clear, effect is remarkable and time-saving Joule law demonstration device.

The technical solution of the utility model is:

A kind of Joule law demonstration device, it comprises demonstration board, power supply, resistance and reometer, it is characterized in that also comprising:

Three test tubes of fixed interval on the demonstration board face are provided with the described resistance and the filled with fluid alcohol of different resistance values in each test tube, the sealing pipe close that all is provided with suitable for reading of each test tube, and resistance two ends wherein pass from the pipe close sealing by lead-in wire;

Penetrate pipe close and connect with the pipe close sealing and fixing on the pipe close of each test tube, the transparent conduit that its inner chamber is communicated with the test tube inner chamber, this transparent conduit are upwards extended and the horizontal scale line that is indicated on the demonstration board face intersects vertically.

Described resistance in each test tube is resistance wire.

Described test tube pipe close is rubber stopper or cork.

The Joule law demonstration device of said structure connects and composes the loop with power supply, switch, resistance and reometer.After the energising, electric current is flowed through, and resistance produces heat in each test tube, and the liquid alcohol temperature in the test tube is raise, volumetric expansion, and the liquid alcohol of expansion rises along conduit.The speed that alcohol liquid rises, height and the electric current of the resistance of flowing through, the size of resistance and the time correlation of energising, and clearly on demonstration board, show, students is understood at a glance.Have the following advantages:

1. rationally distributed, picture is clear, and contrast easily;

2. science is set, and teaching is directly perceived, directly checking;

3. easy to operate, effect is obvious, learns interesting.

Description of drawings

Fig. 1 is a structural representation of the present utility model.

Embodiment

Below, the utility model is described in further detail in conjunction with the accompanying drawings.

Shown in Figure 1, be structural representation of the present utility model.By among the figure as can be known, on demonstration board 10, be provided with all uniformly-spaced horizontal scale line 9 one A, B, C, D; Below scale mark 9, be fixed with perpendicular three the clear

glass test tubes

1,2,3 of filling alcohol 4 putting in lateral separation, all be provided with the pipe close 5 that cork or rubber are made on the mouth of pipe of each test tube; Each invisible spectro alcohol 4 has different resistance resistance---resistance wire R1, R2, R3 respectively.The lower end of three identical

transparent grass tubes

6,7,8 sees through pipe close 5 respectively, and its inner chamber is communicated with the inner chamber of

test tube

1,2,3, and it is mutual vertical with the horizontal scale line 9 of demonstration board 10 upwards to extend;

Grass tube

6,7,8 respectively with its pipe close 5 sealed attachment, be fixedly connected by mode sticking or hoop with demonstration board 10.The pipe close 5 that cuts open from office as can be known, the two ends of

test tube

1,2,3 internal resistance wire R1, R2, R3, the pipe close 5 that passes separately by the extension line sealing constitutes loops with other resistance, power supply, ammeter and switch etc.; Wherein, after the resistance R 2 in the

test tube

2,3, the R3 serial connection,, constitute the loop again with ammeter A2, switch S and 24V power series; Resistance R 1 in the test tube 1 with ammeter A1, switch S and 24V power series, constitutes another loop again with after test tube current-limiting resistance R0 outward is connected in series.In order to make demonstration clear and attractive in appearance, can in the alcohol of each test tube, add some bright-coloured pigment, and make three conduits, 6,7,8 alcohol fluid columns at same horizontal zero graduation line---be on the A scale mark of horizontal scale line 9.

Embodiment

In the circuit shown in Figure 1, R0=2 Ω, R1=R2=4 Ω, R3=8 Ω.Power supply connects the 24V alternating current, the S that closes a switch, the electric current of ammeter A1, A2 indication is respectively I1=4A and I2=2A, can be on blackboard record.At this moment, guiding student is observed, and three

conduit

6,7,8 alcohol fluid columns rise with different speed respectively, and difference is very obvious.The student can see:

(1) time long more, fluid column is high more.Illustrate that electric heating is relevant with the time, the time is long more, and electric heating is big more.The alcohol liquid-column height that rises in the unit interval, can draw: electric heating was directly proportional with the time of energising.

(2) if do not see test tube 1, only observation

analysis test tube

2 and 3 conduit 7,8.Resistance R 2 and R3 series connection in the

test tube

2 and 3 as can be seen from Figure 1, electric current equates, because R3〉R2, from the liquid-column height difference as can be seen the fluid column of conduit 8 be higher than the fluid column of conduit 7.R3=2R2, the fluid column height of conduit 8 should be 2 times of conduit 7.Illustrate when electric current equates that the big more electric heating of resistance is big more, electric heating is directly proportional with resistance.

(3) relatively when electric heating and electric current, cover in test tube 3 and conduit 8 thereof, only observe test tube 1 and 2 and

conduit

6 and 7; Since R1=R2=4 Ω, I1=2I2, the E line place in the required scale mark 9 of the fluid column in the conduit 6, the B line place in the required scale mark 9 of the fluid column in the conduit 7.Thereby draw: resistance equates that electric current is big more, and electric heating is big more.Provable through experiment repeatedly again: square being directly proportional of electric heating and electric current.

Claims

1, a kind of Joule law demonstration device, it comprises demonstration board, power supply, resistance and reometer, it is characterized in that also comprising:

Three test tubes (1,2,3) of fixed interval on demonstration board (10) face, be provided with the described resistance (R1, R2, R3) and the filled with fluid alcohol (4) of different resistance values in each test tube (1,2,3), the sealing pipe close (5) that all is provided with suitable for reading of each test tube (1,2,3), resistance wherein (R1, R2, R3) passes from pipe close (5) sealing by the two ends lead-in wire;

On the pipe close (5) of each test tube (1,2,3), penetrate pipe close and connect with pipe close (5) sealing and fixing, the transparent conduit (6,7,8) that its inner chamber is communicated with the test tube inner chamber, this transparent conduit (6,7,8) are upwards extended and the horizontal scale line (9) that is indicated on the demonstration board face intersects vertically.

2, Joule law demonstration device according to claim 1 is characterized in that:

Described resistance (R1, R2, R3) in each test tube (1,2,3) is resistance wire.

3, Joule law demonstration device according to claim 1 and 2 is characterized in that:

After resistance (R2, the R3) serial connection in the test tube (2,3),, constitute the loop again with ammeter (A2), switch (S) and power series; Resistance (R1) in the test tube (1) with ammeter (A1), switch (S) and power series, constitutes another loop again with after test tube current-limiting resistance (R0) outward is connected in series.