What is the effect of negative current on galvanometer?

Galvanometer is an instrument used to detect weak currents. In general, a negative current has a similar effect on a galvanometer as a positive current, but it may behave a little differently in the following ways:

Pointer deflection direction

Determine current direction

The direction of the galvanometer pointer deflection is related to the direction of the current passing through it. Normally, when current flows from a particular direction of the galvanometer, the pointer deflects in one direction; When the current flows in the opposite direction, the pointer will be deflected in the opposite direction.

For example, if the current flowing in from the left end of the galvanometer and flowing out from the right end of the galvanometer is specified to be positive, the pointer may be deflected to the right when the positive current is out of date; When the negative current passes, the needle will be deflected to the left.

It affects the interpretation of measurement results

When measuring with a galvanometer, it is necessary to determine the direction of the current according to the deflection direction of the pointer. If there is a negative current, it is necessary to correctly interpret the deflection direction of the pointer to accurately determine the actual current flow direction.

For example, in circuit analysis, the path and direction of current flow in a circuit can be determined by observing the direction of deflection of the galvanometer pointer. If a negative current causes the pointer to reverse deflect, the current situation in the circuit needs to be correctly analyzed according to the known circuit structure and current direction conventions.

Sensitivity and accuracy

Sensitivity change

For some galvanometers, negative and positive currents may have different effects on their sensitivity. The sensitivity of the galvanometer usually refers to its response to weak current, generally expressed by the ratio of the Angle of pointer deflection to the size of the passing current.

For example, some galvanometers may have high sensitivity when measuring positive current, but slightly lower sensitivity when measuring negative current. This may be due to factors such as the internal structure of the galvanometer, material properties or working principles.

Accuracy effect

Negative current may also affect the measuring accuracy of galvanometer. Measurement accuracy refers to the closeness between the measured result and the true value. If the galvanometer has a large error when measuring the negative current, it will affect the accuracy of the measurement result.

For example, in precision measurement, if the galvanometer's response to negative current is not accurate, the measurement results may be biased, which affects the accurate judgment of circuit parameters or physical quantities.

Risk of damage to galvanometer

Overcurrent risk

If the magnitude of the negative current exceeds the rated current range of the galvanometer, it may cause damage to the galvanometer. Excessive current may cause the coil inside the galvanometer to overheat, burn, or damage mechanical components such as Pointers and springs.

For example, in the experiment, if the wrong high amplitude of the negative current into the galvanometer, it may cause the galvanometer instant damage, can not continue to use.

Reverse voltage effect

In some cases, a negative current may be accompanied by the appearance of a reverse voltage. If the galvanometer cannot withstand the reverse voltage, it may be damaged.

For example, in a circuit containing a component such as a diode, a reverse voltage may be generated when the current flows in the opposite direction. If the galvanometer does not have adequate reverse voltage protection measures, it may be broken down by the reverse voltage and damage the internal circuit.