Resistance measurement method, 6 kinds of resistance measurement methods

1) External method --- Figure A.

Ammeter. Are the voltmeter measurements current and voltage r?

The value measured by the voltmeter is the voltage of the resistance r, i.e., u measurement = ur

The value measured by the ammeter is the parallel value of the voltmeter and the resistance, that is, I measurement = IR + IV visible external measurement R measurement R

2) Inscribed method --- Figure B.

The ammeter measures the current of R, i.e., I = IR

The voltmeter measures the series between R and the ammeter, U = UA+UR, so R = U > R, true.

**It's more difficult, let's express it verbally first.

Internal measurement method: the ammeter and the resistance are regarded as a whole, and the resistance measured by the voltmeter in parallel on the outermost (one end is connected to the resistor, and the other end is connected to the power meter) is larger, because the resistance and the ammeter are regarded as a whole, and there is resistance under the non-ideal condition of the ammeter, so the total resistance of the measured resistance ammeter and the resistance to be measured is the sum.

External measurement method: make a whole of the voltmeter and the resistance (both ends of the voltmeter are connected to the resistor), and the ammeter is connected to the outermost edge. The measured resistance is small, because the resistance and the voltmeter are connected in parallel as a whole, and the voltmeter has resistance in a non-ideal state, and the resistance after parallel connection is less than any group, so the measured resistance is the overall resistance, which is less than the actual value of the resistance to be measured.

It should be like this, when I was in high school (that is, last year), it seemed to be called the external method and the internal method, I don't know if it is the same as what you said.

When the resistance to be measured is much less than the internal resistance of the voltmeter, the external measurement method is used.

The special method of measuring resistance is as follows:

1.Ampere method ("ampere" refers to the ampere meter, which is the ammeter; "Resistance" refers to a fixed-value resistance with a known resistance).

2.Ann slip method ("amp" means ammeter; "Slippery" refers to a sliding rheostat with a known maximum resistance).

3.An-box method ("An" means ammeter; "Box" refers to the resistance box staring at the ruler).

4.Volt-resisting method ("volt" refers to the voltmeter, which is the voltmeter; "Resistance" refers to a fixed-value resistance with a known resistance value).

5.Volt-slip method ("volt" refers to voltmeter; "Slippery" refers to a sliding rheostat with a known maximum resistance).

6.Volt-box method ("volt" refers to voltmeter; "box" means resistance box).

Detailed steps.

1. If the equipment requires that only two ammeters can be used, and there is a fixed resistance with a known resistance.

Close the switch and measure the sum of currents i2 through r0 and rx: rx=i2xi1 r0

2. If the equipment of the safety slip method requires that only one current slip meter can be used, and there is a sliding rheostat.

Close the switch and measure the current value i1 when the resistance of the sliding rheostat is maximum (the maximum resistance is RM) and the current value when the resistance of the sliding rheostat is the most difficult: rx=i1xrm (i2-i1).

3. If the equipment requires that only one ammeter can be used, and there is a fixed resistance with a known resistance value.

When S1 is closed and S2 is disconnected, the ammeter measures the current I0 through R0. When S1 is open and S2 is closed, the ammeter measures the calculated formula for the current through Rx: Rx=I0XR0 ix

4. If the volt-volt-proof method equipment requires that only two voltmeters can be used, and there is a fixed value resistance with a known resistance value. Close the switch and measure the voltage U1 and the sum of the voltages at R0 and Rx: Rx=U2XR0 U1

5. If the volt-slip method requires that only one voltmeter can be used, and there is a sliding rheostat.

Close the switch and measure the voltage value U1 at both ends of Rx when the resistance of the sliding rheostat is maximum (the maximum resistance is RM) and the voltage value when the resistance of the sliding rheostat is minimum: Rx=U1XRM (U2-U1).

6. If the volcanic resistance method requires that only one voltmeter can be used, and there is a fixed value resistance with a known resistance value.

When S1 is closed and S2 is disconnected, the voltmeter measures the voltage U0 at both ends of R0. When S1 and S2 are closed, the voltmeter measures the calculation formula of the supply voltage: rx=(u-u0)xr0 u0

The greater the resistance of a conductor, the greater the resistance of the conductor to the current. What are the methods of measuring resistance?

OneMeasurement of electrical resistance

The purpose of measuring the specific resistance value of the resistor is expressed by using the ammeter and voltage.

Voltammetry measurement resistance (specifically divided into "ammeter external method" and "ammeter internal method").

Principle: Ohm's law (r=u i).

1. External connection method of ammeter.

The measured value of the external method is small, and the true value of rx is true = u (i u rv).

2. The internal connection method of ammeter.

The measured value of the ammeter is too large, and the true value of Rx is R-true = (U-IRA) i

3. Selection of measurement methods.

When rx <> ra, inline.

IIHow to measure the resistance

How to measure the resistance

1.Multimeter measurement method.

Turn the multimeter transfer switch to the resistance (1, 10, 100, 1k), select the appropriate range, short the two meter pens and then rotate the zero knob to make the pointer point to the zero line, and then the two meter pens touch the two ends of the resistance to be measured respectively, and the resistance value can be known from the value pointed by the multimeter pointer. (Note: The resistance value is equal to the indicated value multiplied by a multiple of the selected range).

2.Voltammetry.

Equipment: ammeter, voltmeter, sliding rheostat, switch, power supply, resistance to be measured and wires.

There are two kinds of voltammetry resistance measurement methods: internal method and external method.

3.Volcanic method.

Equipment: voltmeter, fixed resistance r0 with known resistance, rx resistance with unknown resistance, switches, power supplies, and wires.

Method. 1. Changing the meter method: that is, measuring the resistance by moving the position of the voltmeter.

Method. 2. Switching on-off method: that is, the resistance is measured by changing the connection of the circuit by closing or disconnecting some switches.

4.Security method.

Equipment: an ammeter, a fixed resistance r0 with a known resistance, a switch, a power supply, a resistance rx to be measured and a wire.

Method. 1. Change the meter method: that is, measure the resistance by changing the position of the ammeter.

Method. Second, the switch on and off method:

a.Short-circuit method.

b.Open Circuit Method.

5.Ann slip method.

Equipment: ammeter, sliding rheostat with a known maximum resistance of r, switch, power supply, resistance to be measured and wires.

6.Volt-slip method.

Equipment: voltmeter, sliding rheostat with a known maximum resistance of r, switch, power supply, resistance rx to be measured, and wires.

The above describes the measurement and method of resistance, when it is necessary to measure the resistance, you can choose the most effective method according to the specific situation.

You can get it for free

WhenVoltmeterWhen the internal resistance is much greater than the resistance value to be measured, the external method is used, and the current flowing through the voltmeter is very small and negligible, so it is doneAmmeter. The measured current is basically the current internal method that flows through the resistance to be measured, when the internal resistance of the ammeter is much less than the resistance value of the resistance to be measured, the internal connection method is used, and the voltage obtained by the ammeter is very small at this time, which is negligible, so the voltmeter is measured.

There are two basic lines for measuring resistance by voltammetry

The ammeter is connected internally and externally. Let the resistance to be measured be the differential band R, the voltage on it is ur, the current through it is IR, the voltmeter resistance is Rv, the voltage on it is UV, and the current passing through it is IV; The ammeter resistor is Ra, the voltage on it is UA, and the current passing through it is IA.

In the experiment, if you don't know the resistance range of the resistance to be measured, you can first connect the ammeter and the resistance to be measured in series to the circuit, turn on the power supply, write down the ammeter reading, and then connect the voltmeter to both ends of the resistance to be measured. If the change in the ammeter reading is small, the virtual balance external connection method is used.

The ammeter has a very small resistance, so when the resistance value of the measured resistance is large, the internal method can be used, at this time, the current data is accurate, and the voltage data is large, and because the measured resistance is large, the voltage component of the ammeter is very small, so the error is very small.

When the resistance to be measured is small, use the external method. At this time, the voltage data is accurate, and the current has the current component of a voltmeter, but because the internal resistance of the voltmeter is very large, the current of the component is very small, so the error will be small.

According to Ohm's law, if the voltage v at both ends of the resistor and the current i through the resistor are measured, the resistance value r (r = v i) can be calculated. This method of measuring resistance is called volt-ampere. The principle of voltammetry is simple and convenient to measure, but due to the influence of the internal resistance of voltmeter and ammeter, it often brings obvious systematic error to the measurement results, and in order to reduce the measurement error, it is necessary to choose the appropriate experimental method and appropriate instrument in the experiment.

Experimental Overview] According to Ohm's law, if the voltage v at both ends of the resistor and the current i through the resistor are measured, the resistance value r (r = v i) can be calculated. This method of measuring resistance is called volt-ampere. The principle of voltammetry is simple and convenient to measure, but due to the influence of the internal resistance of voltmeter and ammeter, it often brings obvious systematic error to the measurement results, and in order to reduce the measurement error, it is necessary to choose the appropriate experimental method and appropriate instrument in the experiment.

Objectives: 1. To master the method of measuring electrical resistance by volt-ampere method;

2. Learn to use constant current source, stable voltage source and digital multimeter;

3 Used as a graph to process data.

Experimental principle] The principle of volt-ampere resistance measurement is shown in the figure above, after measuring the voltage and current of the resistance with a meter, the resistance value can be calculated by Ohm's law r = v i. There are two wiring methods for volt-ampere resistor measurement, due to the influence of the internal resistance of the meter, there is always a method error no matter which connection method is used, but the correct result can be obtained after correction.

The answer is supplemented. In practice, multiple measurement methods are often used to change the voltage and current in the measurement circuit to obtain a set of voltage and current values and make a volt-ampere curve of the component. The volt-ampere curve of pure resistance should be a straight line through the origin, and the resistance value of the component can be obtained by finding the slope of the straight line using the graphing method or the least squares method.

This could be something from a book, right? The so-called multiple methods of measuring resistance are actually Ohm's law: the voltage drop across the measured resistor is known to calculate the current, and the voltage divided by the current is equal to the resistance.

If you only have an ammeter in hand, you can also calculate the resistance value by measuring the current.

Voltammetry to measure resistance.

Multimeter to measure resistance.

The bridge method measures the resistance.

Half-bias method to measure resistance.

The compensation method measures the resistance.