In this article our experts will try to address some common questions [Frequently Asked Questions (FAQs)] regarding the Vernier Caliper and its usage as well as clear up some conceptual problems faced by beginners.

**Q.1: Why use a vernier caliper instead of a regular meter rule?**

Ans: A vernier caliper offers a lot more accuracy than a regular meter rule. We can measure lengths up to a millimeter on a regular meter rule but a vernier caliper with 10 equal divisions on the vernier scale allows us to measure lengths as small as 0.1 mm accurately

**Q.2: What is the principle behind the vernier caliper?**

Ans: The principle behind the vernier scale lies in the difference between the divisions on the main scale and the vernier scale. This difference is very small and usually it is such that 9 divisions on the main scale are equal to 10 divisions on the vernier scale. This means that only one division on the vernier scale will coincide with the main scale division when a measurement is made and this coincident point is used to find the vernier scale reading.

**Q.3: What is meant by the least count?**

.Ans: **The least count** refers to the smallest measurable length by the vernier caliper. It can be found by dividing the difference of 1 Main scale division by the number of divisions between two vernier scale values (usually 10). i.e 1 Main Scale Division/10.

**Q.4: What are the lower jaws of a vernier caliper used for?**

Ans: The function of the lower jaws is to measure the outer diameter of an object such as a tube, sphere or cylinder.

**Q.5: What are the upper jaws used for?**

Ans: The function of the upper jaws is to measure the inside diameter of an object such as a tube, pipe or hollow cylinder.

**Q.6: What’s the thin moving strip behind the main scale for?**

Ans: That strip is what enables us to measure the depths of objects such as tubes or the depth of liquid inside a container.

**Q.7: If there are two vernier calipers with different number of equal divisions on the vernier scale. One with 10 and the other with 50 divisions. Which one would be more accurate?**

Ans: The one with the smaller least count would be more accurate. The least count of the caliper with 10 divisions would be = 0.1 mm (1 Main Scale Division/ No of Divisions).

The one with 50 divisions will have a least count of = 0.02mm.

So as you can see the one with the more divisions can measure a smaller value and is therefore more accurate.

**Q8: What is meant by the Zero Error? **

Ans: If the empty jaws of a vernier caliper are closed and the zero value of the main scale does not line up with the zero value of the vernier caliper then that **vernier caliper has a zero error**.

**Q.9: What formula should be used to measure the least count?**

Ans: The least count can be measured using the formula **Least Count = S/N**

where **S= 1** Main scale division and

N= the no of divisions on the vernier scale between two values.

**Q.10: What formula is used to calculate the volume of a cylinder?**

Ans: The volume of a cylinder can be found using the formula:

**V=pi x r^2 x L **

Where, V= the volume of the cylinder which we need to find,

pi = 22/7 = 3.14159 ,

r= radius of the cylinder and

L is the cylinder’s length.

**Q.11: What is the formula for the volume of a sphere?**

Ans: The volume of a sphere is calculated using the formula:

**V= 4/3 x pi x r^3**

Where V= the sphere’s volume,

r = the sphere’s radius and

pi = 3.14159.

**Q.12: How can we calculate the total reading of the vernier caliper?**

Ans: **The total reading** is calculated using the formula:

**Total Reading = Main Scale Reading + ( n x L.C)**

Where M.S.R= main scale reading,

n= no of divisions till the coincident value of the vernier scale and

L.C = least count of the vernier caliper.

**Q.13: What are the types of zero errors that can occur in a vernier caliper?**

Ans: There are **two types of zero errors** possible in a vernier scale. They are called

- Positive zero error
- Negative zero error

Ans: When the two empty lower jaws are closed the zero mark on the vernier scale should line up exactly with the zero mark on the main scale. If the zero mark on the vernier scale is to the right of the main scale zero then this is a positive zero error. The reading of the vernier scale at the zero position should be subtracted from all subsequent readings to eliminate this error.

For example: If the zero mark on the vernier scale is to the right of the main scale zero in a closed position and the coincident value on the vernier scale is 1, then the total corrected reading would be **Total Reading – (1xL.C).**

**Q.14: What is meant by negative zero error and how can it be eliminated?**

Ans: When the lower jaws are brought in contact and the zero mark on the vernier scale lies to the left of the main scale zero mark then this is known as a negative zero error. The reading on the vernier scale in this position should now be added to all subsequent readings to obtain an accurate value.

For Example: If the zero mark on the vernier scale lies to the left of the main scale zero and the coincident value is 8 then the correct total reading would be; **Total Reading + (8 x Least Count).**

if zero of the verneir callipers lies in between two values of main scale division, then which value should we take?

There are two readings you need to take, one is on the main scale before the 0 of the Vernier scale. This reading is called the Main scale reading. The other reading you need to take is the Vernier scale reading, the division of Vernier scale that exactly matches with any division of the main scale is the Vernier scale reading but that is multiplied with the fractional part to give a complete Vernier scale reading. Later it the Vernier scale reading and the main scale reading is added to give the final reading. You can see this article for more details Reading Steps.

Why there are two digits after the decimal in a vernier caliper