an electromechanical instrument for detecting and measuring small electric currents, typically used in educational and scientific settings. The "30-0-30" range indicates a measurement scale from \(-30\) to $+30$mA, with the "0" in the center for detecting current direction, while the "300G" may refer to a specific model or a label on the device's casing rather than a magnetic field strength in Gauss, as the current is measured in milliamperes (mA).
Features
Current range: The meter is designed to measure a current from $-30\(mAto\)+30$mA, with a central zero point that allows for the detection of the current's direction.
Purpose: It's a sensitive device used to detect the presence and magnitude of small electric currents. It's ideal for experiments involving circuits, including measuring current strength, finding a "null point" in a circuit, and demonstrating electromagnetic induction.
Mechanism: It operates on the principle of a moving coil in a magnetic field. When current flows through the coil, it produces a deflection of the pointer.
Accuracy: The accuracy is often specified to a certain percentage, such as \(\pm 2.5\%\).
Design: Many models are analog, with a sturdy plastic case, lock-type terminals, and often color-coded terminals for easy connection. How to use