Vernier Caliper - Zero Errors and how to overcome them

Zero Error:

 When zero of the vernier scale does not co-inside with zero of the main scale.

 
No Zero Error:

Positive Zero Error:

When zero of the vernier scale is ahead of zero of the main scale.

        

As the 3rd vernier division is co-insiding with main scale, hence zero error is 

 ZERO ERROR = VERNIER SCALE DIVISION x LEAST COUNT

Z.E = 3 x 0.01 cm

      = 0.03 cm 

Negative Zero Error:

When zero of the vernier scale is behind the zero of the main scale.

 Although the 4th vernier division is co-insiding with main scale, zero error is counted from the backward direction i.e -6

  ZERO ERROR = VERNIER SCALE DIVISION x LEAST COUNT

Z.E = -6 x 0.01 cm

      = -0.06 cm  

 

Overcoming a zero error 

Apply:

 Actual (Corrected) Reading = Total (Observed) Reading  - Zero Error