ELECTRONIC BALANCE:-
Most analytical balances used today are electronic balances. Modern electronic balances are convenient to use and are subject to fewer errors or mechanical failures than the mechanical balances. The weighing becomes speedy as the operations like keeping weights, the pan arrest of mechanical balances are eliminated.
Principle of electronic balance:-
There are no weights or knife edges as with mechanical balances. The pan sits on the arm of a movable hanger (H) and this movable system is compensated by a constant electromagnetic force. The position of the hanger is monitored by an electrical position scanner (5) which brings the weighing system back to the zero position. The compensation current is proportional to the weight placed on the pan. This is sent in digital form to a microprocessor that converts it into the corresponding weight value, which appears as a digital display. The weight of the container can be automatically subtracted.
These balances use the principle of electromagnetic force compensation first described by Angstrom in 1895. But they still use the principle of comparing one weight with another. The balance is “zeroed”, or calibrated, with a known weight. When the sample is placed on the pan,its weight is electronically compared with the known. This is form of self-calibration.
A single control bar is used to switch the balance on and off, to set the display to zero.
