Young's modulus by searle's apparatus

[babita]

Homework Statement

What is the point of using the micrometer in determination of young's modulus of a wire using SEARLES APPARATUS ?

2. Homework Equations
wouldn't the micrometer measure the cross sectional area of the wire...and here we need to measure the extension. I know it is related to spirit level going down when the test wire is loaded..but how?

3. The Attempt at a Solution

 

[babita]

Shouldn't a vernier caliper be used?

 

[Dadface]

Shouldn't a vernier caliper be used?

The diagram is labelled incorrectly.Just as you thought a vernier scale(not caliper) is used to measure the extension and a micrometer to measure the wire diameter.

On second thoughts It seems I have referred here to the original Searles design.Having done a quick search it seems that the apparatus can also come in modified and probably improved designs.The original design still gives accurate results but I suggest you google for the other variations.

 

[babita]

oh...thanks :)