Question

The smallest inside micrometer has the graduation marked on the sleeve to a range of:
1. 12 mm
2. 13 mm
3. 14 mm
4. 15 mm

Answer 1

Correct Answer - Option 2 : 13 mm

Explanation:

• An inside micrometer is a precision measuring instrument which measures with an accuracy of 0.01 mm.

Purpose

• An inside micrometer is used to measure the diameter of holes. 
• To measure the distance between internal parallel surfaces like slots

The following are the parts of an inside micrometer

• Micrometer head: It consists a sleeve, a thimble, an anvil and locking screw for extension rods. The smallest inside micrometer has the graduation marked on the sleeve to a range of 13 mm.
• Extension rod: This is fitted in the hole provided in the barrel of the micrometer head. It provides another measuring surface. It is available in different sizes.
• Locking Screw: It is used to lock the extension rods.
• Handle: It is fitted in the threaded hole provided in the micrometer head. It is used to hold the micrometer assembly while measuring deep bores.
• Spacing collar: It is added to the extension rod for additional length. It is available in different sizes.

The range of inside micrometer

• Using the different sizes of extension rods and spacing collars the following ranges of measurement can be taken
  1. 25-50 mm
  2. 50-200 mm
  3. 50-300 mm
  4. 200-500 mm
  5. 200- 1000 mm