How does a beam balance work?
The leveling screws at the base are adjusted to make the pillar vertical. The beam is gently raised by turning the handle. If the pointer does not oscillate almost equally on either side of the central division of the scale, adjust the nuts suitably at the ends of the beam.
Before determining the mass of the body one needs to calibrate the beam balance.
The balance is released and the pointer is allowed to oscillate freely. Three or five successive readings (three to the left and two to the right on the scale against which the pointer turns back during oscillations) are taken. These readings are called the turning points. The average turning point on the left and the average turning point on the right are separately calculated. The mean of these averages gives the zero resting point ( R0).
The method of calculation is given below.
Turning Points (T.P) | |
Left | Right |
X1 X2 X3 |
Y1 Y2 |
Mean T.P | |
| |
Resting Point , |
For finding the sensibility, 10 mg weight is placed in the right pan and the resting point (R1) is determined as before. Then the sensibility S is calculated using the equation (2) explained in the 'Theory' tab. .
The balance is arrested by turning the handle. The given body is placed in the left pan and it is counter balanced by a known mass (W) in the right pan. The resting point (R) is determined. The correct mass of the body can be calculated using the relation (1) explained in the the 'Theory' tab.
Note: The pointer of the beam balance always rests near the pan having less weight.
For Sensibility Checking
After sensibility calculation,
Note: The pointer of the Beam balance always rest near the pan having lesser weight.
To find the weight of the body
Loads in Pan | Turning Points | Mean Turning Points | Resting Point | |||
Left | Right | Left | Right | Left | Right | |
Nil | Nil | R0= | ||||
Nil | 10 mg | R1= | ||||
GIven Body |
W=----g | R= |
1. Sensibility, =................................................g / div
2. Correct mass of the body, = ............................g
=………………kg
The mass of the body = ………...............……kg