1.
Who invented the Micrometer?
Correct Answer
B. William Gascoigne
Explanation
William Gascoigne is credited with inventing the micrometer. He was an English astronomer and mathematician who developed the micrometer in the early 17th century. The micrometer is a precision measuring instrument used for accurately measuring small distances or thicknesses. Gascoigne's invention greatly improved the accuracy and precision of measurements in various fields, including astronomy and engineering.
2.
What is a micrometer used to measure?
Correct Answer
C. Length
Explanation
A micrometer is a precision measuring tool used to measure very small distances or thicknesses with high accuracy. It is commonly used in mechanical engineering, machining, and metalworking to ensure components meet specified dimensions. The tool consists of a calibrated screw and a spindle that moves towards or away from the object being measured, allowing for precise measurement of length.
3.
What is the typical accuracy of a standard micrometer?
Correct Answer
B. 0.01 mm
Explanation
A standard micrometer typically has an accuracy of 0.01 mm (10 micrometers). This high level of precision makes micrometers essential for tasks requiring exact measurements, such as manufacturing and quality control. The micrometer's design, which includes a finely threaded screw mechanism, allows for such precise readings, ensuring parts are manufactured within tight tolerances.
4.
What part of the micrometer is adjusted to take a measurement?
Correct Answer
C. Thimble
Explanation
The thimble of a micrometer is the part that is rotated to move the spindle towards or away from the anvil, allowing for the measurement of an object's dimension. The thimble is graduated with markings that correspond to specific measurements, which, when combined with the markings on the sleeve, provide a precise reading. Rotating the thimble adjusts the position of the spindle, enabling accurate measurements.
5.
What tool is commonly used to measure small dimensions with high precision?
Correct Answer
B. Micrometer
Explanation
The ratchet stop on a micrometer ensures that consistent pressure is applied when taking a measurement. This feature prevents over-tightening or under-tightening, which can lead to inaccurate measurements. By providing a uniform force, the ratchet stop enhances the reliability and accuracy of the readings, making it easier to achieve precise and repeatable measurements.
6.
What material is commonly used to make the anvil and spindle of a micrometer?
Correct Answer
C. Steel
Explanation
The anvil and spindle of a micrometer are commonly made of steel. Steel is used because of its hardness, durability, and resistance to wear, ensuring long-lasting accuracy. These parts must be precisely machined and maintain their shape over time to provide consistent measurements. The choice of steel helps achieve the necessary precision and reliability required in precision measurement tools.
7.
Which part of a micrometer ensures accurate measurements by limiting the pressure applied during measurement?
Correct Answer
B. Ratchet stop
Explanation
The ratchet stop on a micrometer ensures accurate measurements by limiting the amount of pressure applied when measuring an object. This prevents the user from applying too much force, which could distort the measurement. The vernier scale helps in reading measurements more precisely, the anvil is the fixed part against which the object rests, and the spindle is the moving part that advances to measure the object. All these parts work together, but the ratchet stop is key for maintaining consistent pressure and accuracy.
8.
What is the term for the smallest measurement increment a micrometer can detect?
Correct Answer
A. Resolution
Explanation
The resolution of a micrometer refers to the smallest measurement increment it can detect. This is typically 0.01 mm for standard micrometers. High-resolution micrometers can measure even smaller increments, providing more detailed and precise readings. Resolution is a critical specification for applications requiring fine measurements, as it determines the tool's ability to discern small differences in dimensions.
9.
What is the symbol used to measure the readings of a micrometer?
Correct Answer
A. μm
Explanation
The symbol used to measure the readings of a Micrometer is μm. This symbol represents micrometers, which is a unit of length equal to one millionth of a meter. Micrometers are commonly used to measure very small distances or dimensions, particularly in scientific and engineering fields. The symbol μm is derived from the Greek letter mu (μ), which represents "micro" in the International System of Units (SI).
10.
What unit is commonly used to measure small dimensions with a micrometer?
Correct Answer
C. Micrometers
Explanation
A micrometer, often denoted as μm, is a unit of measurement equal to one millionth of a meter. This unit is commonly used to measure very small dimensions with high precision, making it ideal for tasks in mechanical engineering, machining, and various scientific fields. For example, a micrometer can accurately measure the thickness of thin materials or the diameter of tiny objects. This level of precision is crucial for applications that require meticulous measurements. Millimeters, centimeters, and nanometers are also units of length but are used for different scales of measurement.
11.
Micrometers have a fixed spindle.
Correct Answer
B. False
Explanation
Micrometers do not have a fixed spindle. The spindle is movable and can be adjusted to measure different objects with precision.
12.
Correct Answer
C. .125"
Explanation
Since the right side of the micrometer reads zero, we cannot assume it is above or below the mark shown—.100”
13.
Correct Answer
B. .375"
Explanation
Since three marks are shown after .3, and each mark is .025, then this is .375”
14.
Correct Answer
B. .437"
Explanation
Since one mark is shown after .4, and each mark is .025, then this is .425. The indicator on the right shows .012, so this is .437”
15.
Correct Answer
C. .219"
Explanation
Since no mark is shown after .2, and. the indicator on the right shows .019 so this is .219”
16.
State whether the following statement is true or false about micrometers.
"Plastic insulated grips are employed on the frame to reduce heat transfer".
Correct Answer
A. True
Explanation
The statement is true. Plastic insulated grips are used on the frame of micrometers to reduce heat transfer. This helps to prevent the user's hand from getting too hot while using the micrometer, especially when measuring objects that may be at elevated temperatures. The plastic insulation acts as a barrier between the metal frame and the user's hand, reducing the amount of heat that is transferred.
17.
What is the primary purpose of a micrometer's spindle?
Correct Answer
A. To adjust measurement
Explanation
The spindle is a critical component of the micrometer that moves precisely to measure the dimensions of an object. Its movement is controlled by a calibrated screw mechanism, ensuring accurate measurements. The spindle advances or retracts as the thimble is rotated, allowing for adjustments with increments as small as 0.01 mm or finer. By contacting the object being measured, the spindle directly determines the measurement while the anvil remains fixed. This design allows the micrometer to provide highly precise readings, essential for tasks requiring strict dimensional tolerances in engineering, machining, and quality control processes.
18.
Which scale on a micrometer provides fine measurement adjustments?
Correct Answer
B. Vernier scale
Explanation
The Vernier scale enhances the precision of micrometers by enabling the measurement of increments smaller than the main scale's divisions. For example, while the thimble scale typically measures in 0.01 mm increments, the Vernier scale can further refine readings to 0.001 mm. This fine resolution is achieved by comparing the alignment of the Vernier markings with the thimble scale. By observing which marks align, users determine the exact measurement with exceptional accuracy. This capability is crucial in industries like aerospace and electronics, where even minute dimensional differences can affect performance and functionality.
19.
What is the primary use of a ratchet stop on a micrometer?
Correct Answer
B. To provide consistent force
Explanation
The ratchet stop ensures consistent measurement force by limiting the torque applied when turning the thimble. This prevents measurement errors caused by deformation of the object being measured or uneven pressure on the spindle. For example, without the ratchet stop, excessive tightening might compress soft materials, leading to inaccurate readings. The ratchet stop clicks at a specific force, ensuring repeatable measurements with uniform pressure. This feature is particularly vital in precision engineering, where maintaining dimensional consistency across components is essential for proper assembly and operation of machinery or devices.
20.
Why is steel commonly used in micrometer frames and spindles?
Correct Answer
C. It is durable and wear-resistant.
Explanation
Steel is chosen for micrometer frames and spindles due to its hardness, strength, and resistance to deformation. These properties ensure that the instrument maintains accuracy over time, even with frequent use in demanding environments. Steel's low thermal expansion minimizes dimensional changes caused by temperature variations, preserving precision during measurements. For example, a steel spindle resists wear even after repeated contact with hard surfaces, ensuring consistent performance. The durability of steel also reduces maintenance costs and prolongs the lifespan of the tool, making it a reliable choice for precision instruments used in manufacturing and quality control.