Name the part of the vernier callipers which is used to measure the following
external diameter of a tube

Explanation

To determine the part of the vernier calipers used to measure the external diameter of a tube, follow these steps:

1. **Understand the Function of Vernier Calipers**: Recognize that vernier calipers are precision instruments used to measure lengths with high accuracy. They can measure internal and external dimensions as well as depths.

2. **Identify the Components of Vernier Calipers**: Familiarize yourself with the main parts of the vernier calipers, which include the main scale, the sliding scale (vernier scale), and the jaws.

3. **Locate the Jaws**: Note that the vernier calipers have two sets of jaws: the inside jaws and the outside jaws. The inside jaws are used for measuring internal dimensions, while the outside jaws are used for measuring external dimensions.

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