What are the differences between internal and external ammeter connections in the voltammetric method for measuring resistance?
Internal ammeter and external ammeter are two commonly used methods for measuring current in volt ampere resistance measurement. They differ in multiple aspects such as connection method, measurement range, accuracy, and usage conditions. The following will provide a detailed introduction to the differences and characteristics between internal and external ammeters.
Firstly, an internal ammeter refers to directly connecting the ammeter to the resistance element that needs to be measured for current measurement. That is to say, the signal for measuring current flows directly into the ammeter after passing through the resistive element. The connection of the internal ammeter is simple and easy to operate, suitable for measuring small resistances. The main characteristics and advantages of an internal ammeter are high measurement accuracy, fast time-domain response, and strong anti-interference ability. This is because the measurement circuit with an internal ammeter directly contacts the measured object, resulting in minimal signal loss and accurate measurement results. Moreover, the input resistance of the internal ammeter is large, which enables measurement of low resistance. However, internal ammeters also have some drawbacks, such as the need to disconnect the circuit for measurement and being only suitable for measuring small resistances.
On the contrary, an external ammeter refers to connecting an ammeter to the outside of the circuit being tested, indirectly measuring the current by measuring the voltage in the circuit. External ammeter is a method of measuring current by separating the measuring circuit from the measured circuit, and is suitable for various circuit environments. The main characteristics and advantages of an external ammeter are that it is suitable for measuring high currents, does not require disconnecting the circuit for measurement, and does not affect the measured object. The input resistance of an external ammeter is relatively low, making it suitable for measuring high currents. However, external ammeters also have some drawbacks, such as current measurement errors caused by voltage measurement errors, and measurement results being affected by fluctuations in power supply voltage.
In addition to the differences mentioned above, there are also some similarities between internal and external ammeters. Firstly, they are all based on the method of current measurement using voltammetry, and the measurement principle is the same. Both internal and external ammeters need to comply with Ohm's law during measurement. Secondly, whether it is an internal or external ammeter, attention should be paid to the operation method and usage conditions in actual measurement to ensure the accuracy and safety of the measurement.
