Below is a diagram showing a traveling microscope. The device has two scales to obtain horizontal and vertical dimensions. Both dimensions have a vernier scale.This is done by the vernier Principle. It can be accurately measured to 0.01mm.
The main scale is calibrated by half a millimeter and its vernier scale is made by dividing 49 parts of the Main scale into 50 divisions.
Obtain the smallest measure of traveling microscope.
length of 50 divisions in the vernier scale = (0.05mm)*49
length of 1 division in the vernier scale = (0.05mm)*49/50
length of 1 division in the main scale = 0.5mm
therefore the smallest measure = length of 1 division in the main scale – length of 1 division in the vernier scale
= 0.5mm – (0.05mm)*49/50 = 0.5(149/50) = 0.5(1/50) = 0.1(1/10) = 0.01mm
The length of the Venier is exactly 24.5mm. It can be enlarged and viewed as shown in the image below. This can be seen clearly using a lens. This scale is both for the vertical and the horizontal.
How to get readings by using traveling microscope
For example, let’s consider an example of the main scale of the traveling microscope and the Variance scale of it. See the fig below. First, remember the reading always depends on the zero line of the vernier scale. The zero line of the vernier scale is exactly have passed the line of 110.50mm on the main scale. Then, we are recording the main reading = 110.50mm or 11.050cm. Now we have to find the main scale line and a Verner scaling line both coincided(marked with orange arrows). Now we count the divisions from that line to zero line on the vernier scale. Here it is 18. Hence, The reading is 110.50mm + 18(0.01mm) = 110.50mm + .18mm = 11.68mm
Now lets we try to read the reading of this case. See the fig here. When you move your mouse on this diagram, we will have a large image. Now get the position of zero line of the vernier scale.The zero line of the vernier scale is exactly have passed the line of 37.5mm on the main scale. Now record that reading as the main scale reading. Now we have to find the main scale line and a Verner scaling line both coincided(marked with red arrows). Now we count the divisions from that line to zero line on the vernier scale. Here it is 8. Hence 37.5mm + (0.01mm)x8 = 37.5mm + 0.08mm = 37.58mm the reading same as the above example.
Find out the inner diameter and outer diameter of glass tube using by traveling microscope
It is necessary to prepare a traveling microscope for reading As appropriate. Follow the steps below.


 Discover the smallest measure of traveling microscope. This part has already been completed.
 Balance the traveling microscope using a waterlevel.
 The microscopic part and the glass tube place horizontally and same line as the fig here.
 Record the reading (for x_{1} and y_{1}) of crosswire by looking through the microscope as shown the 1fig. Next, same do that for the (x_{2} y_{2}), (x_{3} y_{3}) and (x_{4} y_{4}).

It should be included in the formal order of your practice book. With these readings, we can calculate the inner and outer diameters.
Horizontal outer diameter of tube
Vertical outer diameter of tube
Hence, outer dimeter of tube
Horizontal inner diameter of tube
Vertical inner diameter of tube
Hence, inner dimeter of tube
Now we ready for the Next Lesson. Click NEXT