Voltmeters (voltmeters), ammeters (amperometers), and resistance meters (ohmmeters) are electronic measuring instruments that measure different physical quantities in electrical circuits. They are used to measure voltage, current, and resistance, respectively, and have different operating principles and measuring ranges.
1.Voltmeter (voltmeter):
Measuring Physical Quantities: Voltmeters are used to measure voltage, which is the difference in potential in a circuit.
How it works: The voltmeter is based on the working principle of the voltmeter, usually by connecting a resistive network with high resistance (very large input impedance) so that the load of the voltmeter has less influence on the circuit.
Measuring range: Different models of voltmeters have different measuring ranges, such as millivoltmeter, voltmeter, etc.
2.Ammeter (Ampere Meter):
Measuring Physical Quantities: An ammeter is used to measure the current, which is the flow of electrons in an electrical circuit.
How it works: The ammeter is based on the working principle of the ammeter, which usually needs to be connected in series in a circuit to form a low-resistance path to measure the current.
Measuring range: Different models of ammeters have different measuring ranges, such as milliampere meters, ampere meters, etc.
3.Resistance Meter (Ohmmeter):
Measuring Physical Quantities: Resistance meters are used to measure resistance, i.e., the degree to which the flow of current is hindered in a circuit.
How it works: Resistance meters are based on how ohmic meters work, usually by applying a known voltage to a measuring circuit and then measuring the current flowing through the resistor, thus calculating the resistance value.
Measuring range: Different models of resistance meters have different measurement ranges, for example ohmmeters usually have multiple gears.
Overall, these instruments play an important role in circuit testing and troubleshooting, but when using them, you need to choose the right instrument based on the specific physical quantity being measured, and pay attention to using the correct measurement range to ensure accuracy.
Voltmeters, ammeters, and resistance meters may be similar in appearance, but they have some key differences in their internal structure that reflect the physical quantities they measure and the corresponding measurement principles.
1.Voltmeter (voltmeter):
Internal structure: A voltmeter usually contains an ammeter that has a high-impedance resistor network to reduce the load effect of the meter on the circuit.
Purpose: A voltmeter determines the voltage in a circuit by measuring the potential difference between the two ends of the voltage. Due to its high impedance, the access of the voltmeter does not significantly affect the voltage of the circuit.
2.Ammeter (Ampere Meter):
Internal Structure: The ammeter contains an ammeter whose internal structure requires a low-resistance path in the circuit. This usually involves connecting an ammeter in series directly into the circuit so that current passes through the ammeter.
Purpose: An ammeter is used to measure the strength of an electric current because the flow of current in a circuit causes the deflection of the ammeter pointer. To ensure the accuracy of the measurement, the internal resistance of the ammeter needs to be relatively low to minimize the impact on the circuit.
3.Resistance Meter (Ohmmeter):
Internal Structure: A resistance meter contains a resistance meter whose internal structure involves applying a known voltage to a measurement circuit and then measuring the current flowing through the resistance to calculate the resistance value. The resistance meter may also contain a gear switch device to accommodate different measurement ranges.
Purpose: Resistance meters are used to measure the resistance in a circuit. By applying a known voltage and measuring the current, the resistance value can be calculated by Ohm's law.
While these three instruments may be similar in appearance, their internal structure varies according to their respective measurement principles and uses. When using, it is necessary to select the appropriate instrument according to the specific physical quantity to be measured, and use the correct measurement range to ensure accuracy and avoid interference with the circuit.
The history of the development of these three instruments – voltmeters (voltmeters), ammeters (amperometers), and resistance meters (ohmmeters) – is closely related to the development of the field of electricity.
1.Voltmeter (voltmeter):
The history of voltmeters is closely related to the development of potentiometers. Early potentiometers were used to measure voltage, including the Hoffmann potentiometer (invented by George Simon Ohm in 1745). But true voltmeters were developed in the late 19th century, when the Clark battery (also known as the standard battery) was used as a standard for voltage. At this time, people began to use voltmeters to measure voltage.
Later, as technology advanced, the design of voltameters continued to improve, with more sensitive mechanisms and more accurate measurement methods. Today, the voltmeter has become one of the indispensable instruments in electronic test and measurement.
2.Ammeter (Ampere Meter):
The history of ammeters originated with the development of ammeters. The ampere meter was first invented by the French physicist André Ampère in the late 1820s. Ampere used a coil wound by a conductor and observed that the current passing through the conductor would deflect the coil.
Over time, the ammeter gradually evolved into a modern ammeter, with an improved and optimized internal structure to make it more accurate and sensitive. Modern ammeters often contain protective devices to prevent damage to the circuit or the instrument itself during the measurement.
3.Resistance Meter (Ohmmeter):
The ohmmeter was developed on the basis of resistance meters. The earliest resistance gauges were designed and manufactured by George Simon Ohm in 1827. This instrument measures resistance based on the voltage difference that occurs when an electric current passes through a resistive body.
With the advancement of technology and the development of electrical theory, resistance meters gradually evolved into more accurate and portable ohmic meters. Modern ohmmeters are capable of providing multiple measurement ranges and use more complex circuitry and technology to improve the accuracy and reliability of measurements.
The development of these instruments has evolved with the advancement of electrical theory and technology, from the early basic principles to modern sophisticated instruments, and they have played an important role in electronic engineering and scientific research.