How is electric current measured?
1 Answer
Electric current is measured using a device called an ammeter or an ampere meter. The unit of electric current is the ampere, often shortened to "amp." There are a few methods to measure electric current:
Galvanometer: A galvanometer is a sensitive instrument that can detect small currents. It usually consists of a coil of wire suspended in a magnetic field. When a current passes through the coil, it creates a magnetic field that interacts with the existing magnetic field, causing the coil to move. The degree of deflection is proportional to the current flowing through it. Galvanometers can be calibrated to provide direct current readings.
Shunt Resistor: In some cases, the current being measured might be too high for a standard ammeter to handle. In such cases, a shunt resistor can be connected in parallel with the ammeter. The majority of the current flows through the shunt, while a known fraction of the current passes through the ammeter. By measuring the voltage drop across the shunt resistor, you can calculate the current using Ohm's law (I = V/R).
Hall Effect Sensor: This method is often used to measure current in situations where galvanometers might be impractical, such as in electronic circuits. The Hall effect is a phenomenon where a voltage is generated across a conductor transverse to an electric current and a magnetic field applied to it. Hall effect sensors use this principle to measure the magnetic field generated by the current and then calculate the current itself.
Clamp Meter (Current Clamp): A clamp meter is a non-invasive instrument used to measure current without breaking the circuit. It works by clamping around a conductor and measuring the magnetic field generated by the current flowing through it. The meter then calculates the current based on this measurement.
Current Transformers (CTs): Current transformers are commonly used in high-current applications, such as in power distribution systems. They consist of a primary winding (through which the current to be measured passes) and a secondary winding. The primary current induces a proportional current in the secondary winding, which can then be measured using an ammeter.
Digital Multimeter (DMM): A digital multimeter is a versatile instrument that can measure various electrical quantities, including current. When measuring current, the multimeter is connected in series with the circuit, and it measures the voltage drop across a known internal resistor. The instrument then calculates the current based on Ohm's law (I = V/R).
Remember that when measuring current, it's important to ensure proper connections and use the appropriate method and instrument for the specific application. Always follow safety guidelines and consult the user manual of the measuring instrument for accurate and safe measurements.
Galvanometer: A galvanometer is a sensitive instrument that can detect small currents. It usually consists of a coil of wire suspended in a magnetic field. When a current passes through the coil, it creates a magnetic field that interacts with the existing magnetic field, causing the coil to move. The degree of deflection is proportional to the current flowing through it. Galvanometers can be calibrated to provide direct current readings.
Shunt Resistor: In some cases, the current being measured might be too high for a standard ammeter to handle. In such cases, a shunt resistor can be connected in parallel with the ammeter. The majority of the current flows through the shunt, while a known fraction of the current passes through the ammeter. By measuring the voltage drop across the shunt resistor, you can calculate the current using Ohm's law (I = V/R).
Hall Effect Sensor: This method is often used to measure current in situations where galvanometers might be impractical, such as in electronic circuits. The Hall effect is a phenomenon where a voltage is generated across a conductor transverse to an electric current and a magnetic field applied to it. Hall effect sensors use this principle to measure the magnetic field generated by the current and then calculate the current itself.
Clamp Meter (Current Clamp): A clamp meter is a non-invasive instrument used to measure current without breaking the circuit. It works by clamping around a conductor and measuring the magnetic field generated by the current flowing through it. The meter then calculates the current based on this measurement.
Current Transformers (CTs): Current transformers are commonly used in high-current applications, such as in power distribution systems. They consist of a primary winding (through which the current to be measured passes) and a secondary winding. The primary current induces a proportional current in the secondary winding, which can then be measured using an ammeter.
Digital Multimeter (DMM): A digital multimeter is a versatile instrument that can measure various electrical quantities, including current. When measuring current, the multimeter is connected in series with the circuit, and it measures the voltage drop across a known internal resistor. The instrument then calculates the current based on Ohm's law (I = V/R).
Remember that when measuring current, it's important to ensure proper connections and use the appropriate method and instrument for the specific application. Always follow safety guidelines and consult the user manual of the measuring instrument for accurate and safe measurements.