Type of Micrometer Questions and Answers – Engineering Metrology

1. Which of the following is/are types of micrometer

  1. Inside
  2. Differential
  3. Blade
  4. All of the above

Answer.4. All of the above


A micrometer is a versatile measuring instrument and can be used for various applications by simply changing the anvil and the spindle face.

There are various types of micrometers available in the market. Some of these are

  1. Inside Micrometer
  2. Outside micrometer
  3. Dial Micrometer
  4. Universal Micrometer
  5. Tube micrometer
  6. Screw thread micrometer
  7. Disk micrometer
  8. Depth micrometer
  9. Height micrometer
  10. Differential micrometer


2. The micrometer which is used to measure wire, sphere, shaft is

  1. Inside micrometer
  2. Outside micrometer
  3. Tube Micrometer
  4. Screw thread Micrometer

Answer.2. Outside Micrometer


Outside Micrometer or External micrometer:- It is used for measuring outside diameters, widths, and thicknesses. It consists of a C-shaped frame with a stationary anvil and a movable spindle. The important parts of a micrometer are frame, anvil, spindle, locknut, thimble adjusting nut, sleeve, and ratchet stop.

outside micrometer

It is used to measure circular section parts like outside diameter of shafts or length or thickness of small parts such as a wire.


3. Inside micrometer is used to measure ______

  1. Bore or holes
  2. Depth
  3. Height
  4. Surface area

Answer.1. Bore or Holes


Inside micrometer:-  It works on the same principle as that of the outside micrometer and is used for measuring large diameters say over 50 mm up to an accuracy of 0.01 mm by inserting extension rods of different lengths. The inside micrometer consists mainly of four parts:

  • Micrometer unit
  • Extension rod
  • Handle
  • Spacing collar

Inside Micrometers. Inside micrometers can be used to measure the inside diameter of a bore. To do this, place the tool inside the bore and extend the measuring surfaces until each end touches the bore’s surface. If the bore is large, it might be necessary to use an extension rod to increase the micrometer’s range. These extension rods come in various lengths. The inside micrometer is read in the same manner as an outside micrometer.

Inside micrometer

It is used for measuring bore diameters and slot widths from 50 millimeters to 210 millimeters. For anyone extension rod its measuring range is 20 millimeters. A range of extension rods in stepped lengths is provided in the case with the measuring head.


4. The range of accuracy of an inside micrometer is

  1. 0.05 mm
  2. 0.01 mm
  3. 0.1 mm
  4. 0.5 mm

Answer.2. 0.01 mm


Inside micrometer works on the same principle as that of the outside micrometer and is used for measuring large diameters say over 50 mm up to an accuracy of 0.01 mm by inserting extension rods of different lengths.


5. Which of the following is/are limitations of the inside micrometer?

  1. Inefficient below 50 mm of diameter
  2. Hard to adjust
  3. Both 1 and 2
  4. None of the above

Answer.3. Both 1 and 2


Inside diameter suffers from two important limitations.

(i) It cannot be used to measure small holes less than 50 millimeters in diameter.

(ii) It cannot be easily adjusted once it is in the hole and this affects the accuracy of contact “feel’ that can be obtained.


6. The range of external micrometer is limited to

  1. 50 mm
  2. 25 mm
  3. 10 mm
  4. 100 mm

Answer.2. 25 mm


External Micrometer head limited to 25 mm range. Separate instruments required in steps of 25 mm or by using interchangeable anvils.


7. If the movable spindle is pointed  in nature or in conical shape you are more likely using

  1. Depth gauge
  2. Tube gauge
  3. Height gauge
  4. Screw thread gauge

Answer.4. Screw thread gauge


Screw thread micrometer:-  It is designed to measure the pitch diameter of screw threads to an accuracy of 0.01 mm. In construction, the screw thread micrometer, as shown in Fig. is similar to the outside micrometer with the following differences.

(1) The movable spindle is pointed or in a conical shape

(2) The end of the anvil is of the same form as the screw thread to be measured.

Screw type micrometer

It measures pitch diameters directly. The anvil has an internal ‘vee’, which fits over the thread. Since the anvil is free to rotate, it can accommodate any rake range of thread. However, interchangeable anvils need to be used to cover a wide range of thread pitches. 


8. Which of the following instrument is used to measure depths and groove spacing?

  1. Tube micrometer
  2. Depth Micrometer
  3. Height micrometer
  4. Disk micrometer

Answer.2. Depth micrometer


Depth micrometers are used for measurements of depths, groove spacing, and groove widths.

Depth gauge micrometer

The depth gauge micrometer is also based on the principle of the micrometer. It is similar in construction to an ordinary micrometer, but instead of a frame, it has a shoulder as shown in Fig. These micrometers also have an accuracy of 0.01 mm. A depth gauge micrometer is used for measuring the depth of holes in workshops.


9. In which of the following measuring instrument the scale is reversed as compared to a simple micrometer?

  1. Tube micrometer
  2. Height micrometer
  3. Disk micrometer
  4. Depth Micrometer

Answer.4. Depth Micrometer


A depth micrometer is used for measuring the depth of holes and slots. You must take care when using a depth micrometer because its scales are reversed when compared with the familiar micrometer caliper. Also the measuring pressure tends to lift the micrometer off its seating.

The measuring range is 25 millimeters for any given rods. Typical rods give a range of 0 to 25 mm, 25 to 50 mm, 50 to 75 mm.


10. The disk micrometer is used to measure

  1. Root tangent Length
  2. Triangle Length
  3. Parallel Length
  4. Perpendicular length

Answer.1. Root tangent length


Disk micrometer:- It is used for measuring the distance between two features with curvature i.e root tangent length. A tooth span micrometer is one such device that is used for measuring the span between the two teeth of a gear. Although it provides a convenient means for linear measurement, it is prone to error in measurement when the curvature of the feature does not closely match the curvature of the disk.


11. Which of the following micrometer is used for measuring the thickness of the pipe?

  1. Disk micrometer
  2. Depth micrometer
  3. Tube micrometer
  4. Screw thread micrometer

Answer.3. Tube micrometer


Tube micrometers or ball contact micrometers are designed to measure the wall thickness of tubular parts, such as sleeves and collars. They also can be used for measuring from the inside of holes that are too small for the anvil end of a standard micrometer to be inserted.


12. Which of the following option is correct about the given statements about Digital micrometer?

Statement 1: Digital micrometer has an anvil, spindle, lock nut as Analog Micrometer
Statement 2: It does not require a battery

  1. Only statement 1 is true
  2. Only statement 2 is true
  3. Both the statements are true
  4. Both the statements are false

Answer.1. Only statement 1 is true


Digital Electronic Micrometers

  • A digital micrometer, like a customary micrometer, is used to measure the length, diameter, or thickness of an object.
  • Just as with a customary micrometer, an electronic digital micrometer has an anvil, spindle, lock nut, sleeve, thimble, and ratchet.

Digital micrometer

  • In addition, most digital micrometers have three buttons: ON/OFF or POWER, HOLD, and IN/mm. The micrometer has a fourth button: ZERO for resetting it to zero value.
  • Because the reading is electronically generated and digitally displayed on an LCD (liquid crystal display), a digital micrometer requires a battery. Digital micrometers come in various sizes.


13. Which of the following is/are advantages of Digital micrometer?

  1. Data can be saved
  2. Quick switching between different dimension
  3. Data can be printed
  4. All of the above

Answer.4. All of the above


Advantages to digital micrometers:

(a) measurements are read in a single step on an LCD display.

(b) a button allows for switching between metric and inch measurements.

(c) some versions allow the data to be saved to a USB (universal serial bus) drive or printed.

(d) some versions are designed so that data can be sent wirelessly or with a traditional cable, and (e) can provide for SPC (statistical process control) analysis and documentation.

Note:- The one big disadvantage of an electronic digital micrometer is that it requires a battery. If the battery is dead, the micrometer will not operate. It is always a good idea to have a spare battery in your micrometer case.


14.  What is the accuracy range of stick micrometers?

  1. ±0.005 mm
  2. ±0.05 mm
  3. ±0.5
  4. ±0.0005 mm

Answer.1. ±0.005 mm


The accuracy of stick micrometers is of the order of ±0.005 mm. They are used to measure longer internal lengths. They have a series of extension rods to measure up to the maximum length.


15.  The universal micrometer can be used as

  1. Depth micrometer
  2. Step Micrometer
  3. Outside micrometer
  4. All of the above

Answer.4. All of the above


Universal micrometer:- It has interchangeable anvils such as flat, spherical, spline, disk, or knife edge. It is called universal because of its modular design. The micrometer fitted with the required accessories can function as an outside micrometer, a depth micrometer, a step micrometer, etc.

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