CBSE Class 9 Answered

To measure the mass of an object, following procedure is adopted :

(i) before using the blance, the plumb line is brought just above te pointed projection byt the adjusting screws at the the base . The beam is then raised gently by using the lever and it is ensured that the pointer swings equally on both sides of the zero mark on scale, otherwise it is adjusted with the help of screw nuts.

(ii) The beam is now lowered and given object is placed on the left hand pan.

(iii) The max. approx. weight is placed on the rigt hand pan fronm the wt. box with the help of forceps. Then the lever is turned towards right so that the beam rises and the pointer begins to swing on either side . The side to which the pointer moves , indicates les mass on that side.

(iv) The standard wts. are adjusted till the pointer either remains at the zero mark of scale or it swings equally on both sides of the zero mark. In this position, the total mass of the weights on the right pan gives the mass of the object.

Precautions :- The lever should be gently turned , in order to prevent the knife edges from chipping.

2. The beam should be lowered before adding or removing weights.

3. The weights should be carried with forceps.

4. Wet and hot objects should not be kept in the pan.