Circuit for measuring electromotive force and internal resistance of battery

Abstract

The utility model relates to the technical field of electromagnetic tests, and particularly discloses a circuit for measuring electromotive force and internal resistance of a battery, which comprises the battery, a switch S, a fixed-value resistor R0, a voltmeter V, a resistance box and a lead, and before the switch is closed, the resistance value of a circuit accessed into the resistance box is firstly set. Measuring for six times, and respectively recording the resistance value of the resistance box and the corresponding reading of the voltmeter. And deducing a relational expression of 1 / U and R. And drawing a 1 / U-R graticule. Calculating values of electromotive force and internal resistance of the battery; according to the test circuit, through the Ohm law of a closed circuit, a relational expression of 1 / U and R can be deduced and converted into a linear function in an image, the electromotive force and the internal resistance of the battery are solved according to the slope and the intercept, and the circuit and the test method thereof have the advantages of being simple and convenient to test, high in accuracy, good in experiment effect and the like, and are worthy of popularization and application.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic experiment, in particular to a circuit for measuring the electromotive force and internal resistance of a battery. Background Art

[0002] In high school physics learning, battery electromotive force and internal resistance measurement tests are often carried out. The basic principle is Ohm's law of closed circuits. However, due to different experimental instruments, different measurement schemes can be designed, which are basically adaptations and innovations of volt-ampere characteristics. However, some test devices, such as the selected sliding rheostat, can realize continuous resistance change, but cannot accurately indicate the size of the resistance value connected to the circuit. In addition, some test methods also have problems such as complex testing, difficult to master, and high error rate. To this end, a circuit for measuring battery electromotive force and internal resistance is provided. The test method can realize accurate measurement of battery electromotive force and internal resistance, and the operation is simple and convenient, and the practicability is strong, so as to solve the problems of complex testing and high error rate in the existing battery electromotive force and internal resistance measurement tests using sliding rheostat and other test devices. Utility Model Content

[0003] In view of the problems existing in the prior art, the utility model aims to provide a circuit for measuring the electromotive force and internal resistance of a battery.

[0004] The technical solution adopted by the utility model to solve the technical problem is: a circuit for measuring the electromotive force and internal resistance of a battery, comprising a battery, a switch S, a fixed resistor R0, a voltmeter V, a resistance box and a wire, wherein the battery is connected in series to the switch S through a wire, the switch S is connected in series to the fixed resistor R0 through a wire, and the fixed resistor R0 is connected in series to the resistance box through a wire;

[0005] The two ends of the fixed resistor R0 are connected in parallel to the voltmeter V through wires.

[0006] Specifically, the electromotive force E of the battery is 1.5V, and the internal resistance r of the battery is less than 2 ohms.

[0007] Specifically, the range of the voltmeter V is 1V, and the internal resistance Rv of the voltmeter V is 380.0 ohms.

[0008] Specifically, the fixed value resistor R0 is 20.0 ohms.

[0009] Specifically, the resistance value of the resistor R in the resistor box is adjustable, the resistor R in the resistor box represents the size of the resistance value connected to the circuit, and the maximum resistance value of the resistor R in the resistor box is 999.9 ohms.

[0010] Specifically, the resistance value of the resistor R in the resistor box can be adjusted 6 times.

[0011] Specifically, the switch S is used to connect or disconnect the circuit.

[0012] The utility model has the following beneficial effects:

[0013] The utility model designs a circuit for measuring the electromotive force and internal resistance of a battery, which is converted into a linear function in an image through the expression of Ohm's law of a closed circuit, and the electromotive force and internal resistance of the battery are obtained from the slope and the intercept. This method is an adaptation and innovation of the voltammetry method, and has the advantages of simple testing, high accuracy, good experimental effect, strong practicability, etc., and is worthy of popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the circuit structure for measuring the battery electromotive force and internal resistance.

[0015] Figure 2 It is a grid diagram of the 1 / UR graph disclosed in the embodiment of the present utility model.

[0016] In the figure: R0-fixed value resistor; V-voltmeter; Rv-voltmeter resistance; R-resistance of resistance box; E-battery electromotive force; r-battery internal resistance; S-switch. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely further describe the technical solutions in the embodiments of the utility model. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] Embodiment 1.

[0019] like Figure 1 As shown, a circuit for measuring the electromotive force and internal resistance of a battery includes a battery, a switch S, a fixed resistor R0, a voltmeter V, a resistance box and a wire. The battery is connected in series to the switch S through a wire, the switch S is connected in series to the fixed resistor R0 through a wire, and the fixed resistor R0 is connected in series to the resistance box through a wire; both ends of the fixed resistor R0 are connected in parallel to the voltmeter V through a wire.

[0020] The electromotive force E of the battery is 1.5V and the internal resistance r of the battery is less than 2 ohms.

[0021] The range of the voltmeter V is 1V, and the internal resistance Rv of the voltmeter V is 380.0 ohms.

[0022] The fixed value resistor R0 is 20.0 ohms.

[0023] The resistance value of the resistor R in the resistor box is adjustable. The resistor R in the resistor box indicates the size of the resistance value connected to the circuit. The maximum resistance value of the resistor R in the resistor box is 999.9 ohms.

[0024] The resistance value of the resistor R in the resistor box can be adjusted 6 times.

[0025] The switch S is used to connect or disconnect the circuit.

[0026] There are multiple wires, and the wire model is a U-shaped end multi-strand copper core soft wire with a diameter of 0.2cm and a length of 40cm.

[0027] Embodiment 2 is a method for testing the electromotive force and internal resistance of a battery using the circuit structure of embodiment 1.

[0028] like Figure 1-Figure 2 As shown, after connecting the circuit, follow the steps below to test:

[0029] 1. Setting the resistance value of the resistor box before connecting to the circuit. To protect the voltmeter V, the voltage across the voltmeter V cannot be greater than the full bias voltage of the voltmeter V when the circuit is connected. Therefore, before closing the switch S, the resistance value of the resistor box connected to the circuit cannot be lower than the set resistance value. The set resistance value is calculated based on Ohm's law of the closed circuit.

[0030] 2. Measure and record the resistance of the resistance box and the corresponding reading of the voltmeter V for multiple times. Close switch S and adjust the resistance of the resistance box for 6 times, and record the resistance of the resistance box and the corresponding reading of the voltmeter V respectively.

[0031] 3. Derive the expression for the relationship between 1 / U and R. Based on this circuit, use R, R0, Rv, E and r to derive the expression for 1 / U.

[0032] 4. Draw a 1 / UR grid. Using the measured data, make a 1 / UR graph and draw a 1 / UR grid, such as Figure 2 shown.

[0033] 5. Calculate the values ​​of the battery electromotive force E and internal resistance r. According to the 1 / UR grid diagram, calculate the values ​​of the battery electromotive force E and internal resistance r. E can be rounded to two decimal places, and r can be rounded to one decimal place.

[0034] The test process and the calculation process of related parameters are as follows:

[0035] 1. To protect the voltmeter V, the voltage across the voltmeter V cannot be greater than the full bias voltage of the voltmeter V when the circuit is connected. There is a parallel circuit voltage divider.

[0036]

[0037] Substituting the data, we get R = 7.5Ω. Therefore, before the circuit closes the switch S, the set value of the resistance of the resistance box connected to the circuit must be greater than 7.5Ω. For example, the resistance setting value of the resistance box can be selected as 15.0Ω.

[0038] 2. Close switch S and adjust the resistance of the resistance box 6 times, and record the resistance of the resistance box and the corresponding reading of the voltmeter V. The specific data are shown in Table 1, and a 1 / UR grid is plotted. Figure 2 .

[0039] Table 1 6 resistance box resistance and voltage meter 1 / U test data

[0040]

[0041] 3. Calculation of the relationship between 1 / U and R. According to Ohm's law of closed loop, we have

[0042] Solved

[0043]

[0044] 4. Calculation of the value of the battery electromotive force E and the battery internal resistance r. Substitute the data of R0 and Rv into formula ① and sort them out to obtain

[0045]

[0046] exist Figure 2 In the example above, two sets of data (the first and third points) are selected to obtain the slope of the straight line.

[0047] The solution is E≈1.55V.

[0048] Substitute the data of the first point into formula ② and sort them out, we have

[0049] The solution is r≈1.3Ω.

[0050] Therefore, the battery electromotive force E is 1.55V, and the battery internal resistance r is 1.3Ω. The test is complete.

[0051] The present utility model is not limited to the above-mentioned implementation modes, and anyone should be aware of the structural changes made under the inspiration of the present utility model. Any technical solutions that are the same or similar to the present utility model fall within the protection scope of the present utility model.

[0052] The technology, shape and structure parts not described in detail in the present invention are all known technologies.

Claims

1. A circuit for measuring the electromotive force and internal resistance of a battery, characterized in that: It includes a battery, a switch S, a fixed resistor R0, a voltmeter V, a resistance box and a wire, wherein the battery is connected in series to the switch S through a wire, the switch S is connected in series to the fixed resistor R0 through a wire, and the fixed resistor R0 is connected in series to the resistance box through a wire; The two ends of the fixed resistor R0 are connected in parallel to the voltmeter V through wires.

2. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 1, characterized in that: The electromotive force E of the battery is 1.5V, and the internal resistance r of the battery is less than 2 ohms.

3. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 1, characterized in that: The range of the voltmeter V is 1V, and the internal resistance Rv of the voltmeter V is 380.0 ohms.

4. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 1, characterized in that: The fixed value resistor R0 is 20.0 ohms.

5. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 1, characterized in that: The resistance value of the resistor R in the resistor box is adjustable. The resistor R in the resistor box indicates the size of the resistance value connected to the circuit. The maximum resistance value of the resistor R in the resistor box is 999.9 ohms.

6. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 5, characterized in that: The resistance value of the resistor R in the resistor box can be adjusted 6 times.

7. The circuit for measuring the electromotive force and internal resistance of a battery according to claim 1, characterized in that: The switch S is used to connect or disconnect the circuit.

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