Question

When we can say that vernier callipers is free from zero error?

• A. Zero on main scale coincides with a zero on vernier scale.
• B. Zero on main scale does not coincide with a zero on vernier scale.
• C. It is never free from zero error.
  
• D. It is always free from zero error.
  

Answer 1

The correct option is A Zero on main scale coincides with a zero on vernier scale.

The zero error is defined as such a condition when a measuring instrument registers a reading when there should not be any reading. In the case of vernier callipers, it occurs when a zero on the main scale does not coincide with a zero on vernier scale.

So vernier callipers are free from zero error if zero on the main scale coincide with zero on vernier scale.