A null type of instrument as compared to a deflection type instrument has a higher accuracy or a lover sensitivity
A null type of instrument, when compared to a deflection type instrument, generally has higher accuracy but lower sensitivity.
To understand this, let's start by defining the terms accuracy and sensitivity in the context of measuring instruments:
1. Accuracy: It refers to how close the measurement obtained by an instrument is to the true or actual value. In other words, it represents the instrument's ability to provide correct readings.
2. Sensitivity: It refers to the degree of responsiveness or the ability of an instrument to detect small changes in the measured quantity. In other words, it represents the instrument's ability to detect small variations or differences in the quantity being measured.
Now, let's compare null type and deflection type instruments:
Null type instruments: These instruments are designed to bring the measurement to a null or zero value by adjusting a controlling parameter. Examples include null-type voltmeters, null-type wattmeters, or null-type potentiometers. These instruments typically use a balance or nulling technique to determine the measurement value. Since they aim to bring the measurement to zero, they tend to have higher accuracy as they directly nullify the measured quantity. However, they may have lower sensitivity because the controlling parameter needs to be adjusted precisely to achieve the null condition.
Deflection type instruments: These instruments operate by allowing the measured quantity to deflect a pointer or a display system. Examples include moving coil or moving iron ammeters, voltmeters, or galvanometers. Deflection type instruments indicate the measurement value directly based on the deflection of the pointer alongside a calibrated scale. While deflection type instruments might have higher sensitivity due to the direct deflection, they are generally less accurate compared to null type instruments because there can be errors associated with the mechanical movement of the pointer or other factors.
In conclusion, null type instruments tend to have higher accuracy because they aim to nullify the measured quantity, while deflection type instruments might have higher sensitivity but lower accuracy due to potential errors associated with mechanical movement.