Question

A screw gauge has a negative zero error. Which is correct among these ? ('n' is the total number of circular scale divisions.)

• A. Correction $=$ - coinciding division of C.S $\times$ L.C
• B. Correction $=$ + coinciding division of C.S $\times$ L.C
• C. Correction $=$ + [[n - coinciding division of C.S]$\times$ L.C]
• D. Correction $=$ + [[n + coinciding division of C.S]$\times$ L.C]

Answer 1

The correct option is C Correction $=$ + [[n - coinciding division of C.S]$\times$ L.C]

Total number of division on the circular sale is given as $n$.

Let $p^{th}$ circular scale division coincides with the main scale division.

Negative zero error is calculated by, Correction $=+[L.C.\times (n-p\left)\right]$

So, option C is correct.