Name the part of the vernier callipers which is used to measure the following —

1. External diameter of a tube,

2. Internal diameter of a mug,

3. Depth of a small bottle,

4. Thickness of a pencil.

1. External diameter of a tube — Outside jaws

2. Internal diameter of a mug — Inside jaws

3. Depth of a small bottle — Strip

4. Thickness of a pencil — Outer jaws