plz explain its working and how 2 take its reading

I am giving you some tips about how to use these and try these practically......

1. Vernier Scale- 
there are two scales on vernier callipers-  main scale & vernier scale.

The least count of vernier calliper is 0.1 that is the min. value which can be measured using a vernier calliper.

Ok so suppose you want to measure the thickness of a glass slab.

Then Fit it within the jaws.

Take the main scale reading.

And then see which division of vernier scale is coinciding with any division of main scale.

Note the reading.(called the VSD)

Then multiply by reading with least count.(called the VSR)

Add the main scale reading(MSR) and the  VSR.

Then join both the jaws of the callipers and find the zero error.

Then subtract the zero error from the result.

And you will get the thickness of the glass slab.

Take 2 more readings and then take the mean.

It will give you the final thickness of the glass slab.

Approve it if you found the answer useful.

Then i will also tell you the use of screw gauge.

Approved

Well thnx for approving, Here is screw gauge for you.

There are two scales on screw gauge- main scale & circular scale.
Suppose you want to measure the area of cross section of a given wire.

Then you know the area= Pi*r*r.

So for finding the area you need radius of the wire.

So lets find out the diameter of the wire using screw gauge.

Least count of a screw gauge is 0.01.

So it can measure more accurate values than vernier calliper.

Now to measure lets fix  wire  b/w the anvil & spidle(see the diagram above).

Now take the main scale reading.(also called sleeve).

Now see which circular scale(thimble) division is coinciding with 0 of the sleeve.

Note that reading.

Multiply it by least count.(multiplied result is called CSR)

Now add sleeve reading and CSR.

Subtract the zero error.

Take this reading thrice.

Find the mean you will get the result.

Feel free to ask any question.

I hope you know how to find zero error. However if you dont you can ask.

hi! your explanation of how to find reading for vernier scale and screw gauge has helped me out well. can you plzz tell me how to find the zero error for both of the things ? thank you