4.0.0. MICROMETER SCREW GAUGE :

4.0.0.  MICROMETER SCREW GAUGE :
Micrometer Screw Gauge is used to measure smaller lenght or distance such as the diameter of a , more accurately.

4.1.0.  DIAGRAM OF MICROMETER SCREW GUAGE:

MICROMETER SCREW GAUGE :
Micrometer Screw Gauge is used to measure smaller lenght or distance such as the diameter of a , more accurately.

4.2.0  DIAGRAM OF MICROMETER SCREW GUAGE:

4.3.0.  .SCALES OF MICROMETRE SCREW GUAGE:
A micrometer screw gauge has two scales : the main scale and the vernier scale.

4.3.1.  MAIN SCALE:
The main scale of a micrometer is calibrated in mm. The calibrations of the main scale of micrometer screw gauge vary depending on the range of measurement that the micrometer screw gauges are meant to measure. I will not centre on the main scale.
4.3.2.  VERNIER SCALE:
The vernier scale has 50 equal divisions. Each divisions is obtained by dividing 5 by 10. The vernier scale move a distance of 0.5mm along the main scale when it make 1 revolution by turning round once. One division on the vernier scale equal to 0.5/50 which equal to 0.01mm on the main scale.

4.4.0.  ACCURACY OF MICROMETER SCREW GAUGE :
The accuracy of a micrometer screw gauge is 0.01mm or 0.001cm. This means the that the smallest distance that a micrometer screw gauge can measure is 0.01mm or 0.001cm.

4.5.1.  ACCURACY OF AN INSTRUMENTS :
Accuracy of an instrument is the smallest distance (or value of a particular quantity) that the instrument can measure correctly.

4.5.2.  STEPS TO FOLLOW WHEN READING A MICROMETER SCREW GAUGE :
Step I.
Read and record the reading of the main scale
Step II.
Read and record the reading of the vernier scale at the point where the main scale and the vernier scale coincide.
Step III.
Multiply the reading of the vernier scale by the accuracy of the vernier scale which is 0.01mm
Step IV.  
Add the result of step III to the main scale reading of step I to get the final answer which is the reading of the vernier calliper.

4.5.3.  Worked Examples:
What is the readings of the reading of the micrometer meter screw gauges as shown in the figures below?

Solution:
Reading of main scale.         =   4.50 mm
Reading of vernier scale      =    10               Reading of vernier scale x accuracy of vernier calliper  = 10 x 0.01 = 0.10 mm
Add the result of step III and step I to get the reading of the micrometer screw gauge.                         =  4.50 + 0.10   =    4.60 mm
Reading of vernier calliper               =     4.60 mm  

Solution:
Reading of main scale.         =   22.0 mm
Reading of vernier scale      =   33               Reading of vernier scale x accuracy of vernier calliper  = 33 x 0.01 =   0.33 mm
Add the result of step III and step I to get the reading of the micrometer screw gauge.                         =  22.0 + 0.33   =   22.33 mm
Reading of vernier calliper               =     22.33 mm

Solution:
Reading of main scale.         =   3.25 mm
Reading of vernier scale      =  13  
        
Reading of vernier scale x accuracy of vernier calliper              = 13 x 0.01 = 0.13 mm
Add the result of step III and step I to get the reading of the micrometer screw gauge.    =  3.25 + 0.13
                                                                                          =  3.38 mm
Reading of the micrometer meter screw guage     =     3.38 mm  

4.6EXERCISES:
what are the reading of the micrometer meter screw gauges as shown in the figures below?
1.