Micrometer Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. What is the use of a ratchet stop in a micrometer?

1. Maintain uniform measuring pressure
2. Provide measuring surface
3. Prevent motion of the spindle
4. Forms measuring tip

Ans. The correct answer is a. Maintain uniform measuring pressure

Explanation: To ensure a uniform measurement pressure, a ratchet stop is provided at the end of the thimble cap. Standard conditions of measurement are attained by ratchet stop.

Ques. Which of the following is incorrect about the micrometer?

1. The screw has 10 or 20 threads per cm
2. The thimble and barrel should have a dull finish
3. The total travel of the measuring spindle is called the measuring range
4. The graduated surface diameter of the barrel should be 5 mm

Ans. The correct answer is d. The graduated surface diameter of the barrel should be 5 mm

Explanation: Thimble and barrel should be dull to facilitate reading. The barrel's graduated surface diameter should not be less than 10 mm.

Ques. What is the total error in a micrometer?

1. Positive and negative deviation from the zero point
2. Deviation from measurement of a nominal dimension
3. Maximum difference between ordinates of cumulative error
4. Error in parallelism

Ans. The correct answer is c. Maximum difference between ordinates of cumulative error

Explanation: The deviation of measurement from a nominal dimension is referred to as cumulative error. It contains defects such as thread errors, face measurement problems, and so on. The total error is the maximum difference between the ordinates of cumulative error.

Ques. How many divisions are graduated on thimble?

1. 25
2. 20
3. 45
4. 50

Ans. The correct answer is d. 50

Explanation: Graduation lines should be engraved clearly. On a thimble, there are 50 divisions, each representing 0.01mm.

Ques. Which of the following is incorrect?

1. Blade-type micrometer has a non-rotating spindle
2. V-Anvil micrometer caliper is used to check out of roundness
3. Self-centering inside micrometer has an interchangeable measuring head
4. Tube wall thickness can be measured by an ordinary micrometer

Ans. The correct answer is d. Tube wall thickness can be measured by an ordinary micrometer

Explanation: Because of the concavity of the interior surfaces, a standard micrometer cannot be used to measure tube wall thickness. The anvil is cylindrical in shape, and the spindle axis and anvil axis are perpendicular.

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Short Answers Questions [2 Marks Questions]

Ques. What is a micrometer?

Ans. A micrometer, often known as a screw gauge, is a regularly used tool for measuring precise physical quantities. Micrometers are used in industrial engineering and machining to accurately measure components together with meteorological equipment such as dials, verniers, and digital calipers.

Ques. What is the least count of a micrometer?

Ans. The least count of a micrometer refers to the lowest value that it can measure. It can also be defined as the ratio of the screw pitch to the number of divisions on the scale.

The formula for the least count of a micrometer is given by

Least Count = Pitch / Number of circular scale divisions

Ques. What is a locknut in a micrometer?

Ans. A locknut is a component that, when tightened, keeps the spindle steady. Locknut in the micrometer is provided to lock the reading after setting it over the workpiece.

Ques. List seven parts of the micrometer.

Ans. The seven parts of the micrometer are

• Frame
• Anvil
• Barrel
• Screw
• Locknut
• Spindle
• Ratchet stop

Also Read:

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Long Answers Questions [3 Marks Questions]

Ques. What are the applications of micrometers?

Ans. The applications of micrometers are as follows

• A micrometer is commonly used in engineering and manufacturing to measure threads, apertures, bolts, joints, rods, and threaded inserts. Micrometers can also be used in other industries to measure mechanical items such as springs and bearing gears.
• Because of its small size, a micrometer is widely used as an electronic device. They are frequently used as precision measuring instruments in the industry and are regarded as essential equipment.
• Micrometers are also commonly used in a variety of medical applications, including dental, optical, and biomedical applications, as well as mechanical, chemical, and aeronautical applications. They are highly effective for measuring small amounts of bacteria and pathogens.

Ques. What are the working principles of a micrometer?

Ans. A micrometer operates on the principle of a screw and a nut. It allows for rotation of the barrel-like structure, also known as the Thimble, which is used to estimate the distance between two objects. 

• A micrometer's screw is attached to a thimble, which is a concentrated cylinder attached to the micrometer. 
• To obtain precise results, the circumference of the thimble is split into equal parts of the micrometer.
• When a screw is tuned in a circular motion through a nut, its axial movement equals the screw pitch used in the specific micrometer. The screw's degree of rotation will be directly or indirectly connected to the absolute value of axial movement.

Ques. What are the steps for using a micrometer?

Ans. The following are the steps for using a micrometer

• Choose an appropriate micrometer size based on the size of the workpiece. Typical measurement ranges are 0 to 25 mm, 25 to 50 mm, 125 to 150 mm, and up to 575 to 600 mm.
• Check for zero errors in measurement.
• After putting the object between the two measurement faces, rotate the thimble until the spindle contacts the workpiece. Rotate the ratchet until it starts to slip away from the thimble.
• Now, take a measurement of the primary scale (the scale on the sleeve), say 05.00mm.
• Locate the position on the sleeve or main scale where the thimble meets the reference line to take a thimble reading.

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Very Long Answers Questions [5 Marks Questions]

Ques. A micrometer screw gauge has a positive zero error of 7 divisions, such that its main scale is marked in 1/2 mm and the circular scale has 100 divisions. The spindle of the screw advances by 1 division complete rotation. If the screw gauge reading is 9 divisions on the main scale and 67 divisions on the circular scale for the diameter of thin wire, calculate 

1. Pitch 
2. Least Count 
3. Observed diameter 
4. Corrected diameter

Ans. Given

• Number of circular scale divisions = 100
• Marking of main scale = 1/2 mm
• Main scale reading = 9 divisions
• Circular scale reading = 67 divisions
• Positive zero error = 7 divisions

1. Since the main scale is marked in 1/2 mm, therefore

Pitch = 1/2 mm = 0.5 mm = 0.05 cm

2. Leat count of the micrometer screw gauge is given by

Leat Count = Pitch/number of circular scale divisions

⇒ Leat Count = 0.05 / 100 = 0.0005 cm

100. Main scale reading = 9 divisions = 9 x 1/2 mm = 4.5 mm = 0.45 cm

Circular scale reading = 67 divisions

Therefore, Observed diameter = Main scale reading + (Least Count x Circular scale reading)

⇒ Observed diameter = 0.45 + (0.0005 x 67) = 0.4835 cm

500. Positive zero error = 7 divisions

Correction = - (Error x Least Count)

⇒ Correction = - (7 x 0.0005) = - 0.0035 cm

Therefore, Corrected diameter = Observed diameter + Correction

⇒ Corrected diameter = 0.4835 + (- 0.0035) = 0.4800 cm

Ques. What is the difference between a micrometer and an vernier caliper?

Ans. The differences between a micrometer and an vernier caliper are

Ques. What are the similarities between the vernier caliper and the micrometer screw gauge?

Ans. The following are the similarities between the vernier caliper and the micrometer screw gauge

• Vernier calipers and Micrometre screw gauges have applications in industries such as engineering, metallurgy, and carpentry.
• Both are simple to use and simple to measure.
• To some extent, both the Vernier caliper and the micrometer screw gauge may have zero error. The zero error, on the other hand, can be calculated and eliminated.
• Both are capable of measuring small dimensions. They simply differ in this aspect in terms of accuracy.
• The amplification mechanism of the main scale is used by both micrometer screw gauges and Vernier calipers (the scale is amplified into small dimensions).
• Vernier Callipers and Micrometre Screw Gauges are both available in digital forms.

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