null detector การใช้

• A null detector is one that functions to identify when a given value is zero.
• This field is detected by a highly sensitive magnetometer, acting as a null detector.
• When using a comparator as a null detector, there are limits as to the accuracy of the zero value measurable.
• The signal of this null detector thus is a measure for the equality of the currents; in particular it is zero if the two currents are of exactly equal magnitude.
• Kelvin Varley dividers are therefore usually applied in conjunction with a null detector to compare their output voltage against a known voltage standard, e . g . a Weston cell ( which must also be used without drawing current from it ).