Q. Define Physical balance and Electronic Balance and explain how it is used to measure mass.

 1. The Physical Balance

            The Physical balance is an instrument used for measurement of mass. It is mostly used in laboratory. It works on the principle of moments. It consists of a light  and rigid beam of brass, a metallic pillar, a wooden base, two pans, a metallic pointer and an ivory scale. The plumb line indicates whether the balance is horizontal. In ideal condition the plumb line is aligned with the end of the knob fixed with the pillar.

            When the beam is horizontal the pointer remains on zero mark on the ivory scale. The whole box has leveling screws at the bottom to set it to horizontal. The device is enclosed in a glass box to avoid wind effects.

2. The Electronic Balance

            The digital mass meter is an electronic instrument configured with integrated circuits and it works on the principal of balancing the forces.The device is turned on and set to zero then object is placed on the plate. The reading on the screen gives the mass of object. The electronic balance is available in different ranges of measurement such as micro gram, milligram and kilogram etc.