A vernier scale is a measuring device helps to measure more precisely.

This is used to measure,

#### 1. Inside Dimensions

**Used:** Upper set of jaws.**Measurements: **Diameters of holes, inside dimension of any hollow object**Eg: **Diameter of hole in a wood, Diameters of holes in pipes, cylinders. inside dimension any hollow object.

#### 2. Measuring Outside Dimensions

**Used: **Lower set of jaws. **Measurements: **Lenght of an Object, Outer diameter**Eg:** Outer diameter of a pipe, Length of an object.

#### 3. Measuring Depth

**Used: **Depth probe on the rear part.**Measurement:** Depth of a hole.

**Zero error**

When the vernier is closed, "0" on the main scale is aligned with the "0" of vanier scale. Sometimes both "0" markings of the scale doesn't get alinged. This creates an error known as Zero error.

The formula to use a vernier caliper with zero error

**Actual reading = main scale + vernier scale - (zero error)**

**Zero error examples,**

**1. Positive zero error**

When jaws are closed, Reading = 0.10mm.

If so the **zero error** is named to as +0.10mm.

If Reading = 14.00 mm + 0.54 mm

According to the **formula**: **Actual reading = main scale + vernier scale - (zero error)**

Actual reading = 14.00 + 0.54 - (0.10) = 14.44 mm

**2. Negative zero error**

When jaws are closed, reading = -0.10 mm

If so the **zero error** is named to as -0.10 mm.

If reading = 14.00mm + 0.36 mm

According to the formula **Actual reading = main scale + vernier scale - (zero error)**Actual reading = 14.00 + 0.36 - (-0.10) = 14.46 mm

## Practical Video - How to use a vernier caliper at your lab!