What should I pay attention to when measuring the internal resistance of a galvanometer? Can it be m

Basic parameters: 1 Nominal resistance: The nominal resistance value on the resistor is called the nominal value.

Units: , k, m. The nominal value is marked according to the standard series set by the state, and is not arbitrarily calibrated by the producer.

Not all resistors are present. 2 Allowable Error: The large allowable deviation range of the actual resistance value of the resistor from the nominal value is called the allowable error.

Error**: f, g, j, k....(Common error ranges are: ,, 1%, 2%, 5%, etc.).

3. Rated power: refers to the allowable power consumption on the resistor under the condition that the performance of the resistor is not damaged or basically changed under the condition that the surrounding air is not circulated at the specified ambient temperature, assuming that the surrounding air is not circulated. The common ones are 1 16w 8w 4w 2w w w 、...

When you say Ohm's law, I guess I mean voltammetry. Generally, because the internal resistance of the ammeter is very small, the error measured by voltammetry is too large. When designing the circuit, the internal resistance of the power supply used should not be too large, and it is necessary to pay attention to the contact resistance.

Generally, bridge measurements can be used. The Kelvin double bridge we have studied measures low resistance. Consider using a potentiometer to measure.

Due to the relatively large current through the ammeter, attention should be paid to the protection circuit during the design, and the measurement time should be as fast as possible each time.

OK. When measuring the internal resistance of a galvanometer, simply use the galvanometer as a resistor.

All methods of measuring resistance can be used to measure the internal resistance of the galvanometer, the difference is to ensure that the current through the galvanometer does not exceed IG, so as not to damage the galvanometer.

Of course, it can be measured with an electric bridge. Use the galvanometer as an arm of the bridge. How to ensure that the current through the galvanometer does not exceed IG, as long as a voltage regulating circuit is added to the power supply to control the voltage of the power supply.

1) A brief description of Ohm's law is that in the same circuit, the current passing through a certain section of conductor is directly proportional to the voltage at both ends of the conductor and inversely proportional to the resistance of this conductor. This law was proposed by the German physicist Georg Simon Ohm in April 1826 in "Determination of the Law of Conductivity of Metal Defects"**.

2) Ohm's law formula i=u r

Note: 1. The i, u, and r in the formula must be for the same circuit 2. The units should be unified.

The unit of the electric calendar Li Liu I is An (A).

The unit of voltage u is volts (V).

The unit of resistance r is ohms ( ).

Addendum: There are different opinions, and the Kelvin bridge I mentioned refers to the DC bridge. You use Ohm's law to measure it, and no matter how you do it, there is a systematic error.

An AC bridge measures the impedance of an inductive or capacitive device, and AC resistance is not used for pure resistance.

From the point of view of reducing the error of resistance measurement, the correction of the experimental error from the direct measurement of the ohmmeter, the voltammetry measurement, the compensation method, the Wheatstone bridge, and the Kelvin double bridge are all gradually improved. Why not use a method with higher precision?

What should I pay attention to when measuring the internal resistance of a galvanometer? Because the galvanometer should be connected in series in the circuit when measuring the current, the internal resistance of the galvanometer should be as low as possible so as not to cause too much error.

If there is a known resistance in the current circuit, the voltage method is used, and the Ohm's theorem is the most ideal to measure, because there is no need to connect the galvanometer in series to the circuit, experienced people know that it is much more difficult to connect a device in series than in parallel, and the main role of the bridge is to measure the resistance and impedance (the AC bridge is to measure the impedance) is more troublesome to measure the current, and it is easy to produce errors after conversion.

The galvanometer has a small internal resistance, and the B series circuit can be used as a short connection.

The general method is not measurable, Ohm's law applies to pure circuits Yes.

But the resistance is so small, subtle changes, can you collect it??

OK. [The level is limited, I only know that high school can].

The internal resistance of the ammeter has half deviation method, substitution method, voltammetry method, etc., which are the applications of Ohm's law, but they all have certain errors.

Bridges can measure the internal resistance of any element, including galvanometers. The accuracy of the measurement depends mainly on the sensitivity of the sensitive galvanometer on the bridge (not the resistance to be measured).

Because when the galvanometer indicates 0, that is, the bridge balance can be measured according to the formula, for the insensitive galvanometer, it will not be able to measure because of the weak current, resulting in the bridge century unbalance, which affects the accuracy.

In addition, the formula for calculating the resistance of the bridge in balance is that the product of the resistance of the opposing arm is equal.

Yes. It is related to the supply voltage. There are three interfaces on the galvanometer, if the terminal post in the middle is connected, it is equivalent to the internal resistance of the galvanometer, which is actually quite parallel with a switch and large resistance, and then connected in series with the galvanometer.