Fitter MCQ Quiz - Objective Question with Answer for Fitter - Download Free PDF

Explanation:

Shadow Projector

• A shadow projector is an optical instrument primarily used to produce undistorted magnified reflected images of an object. By projecting shadows of the object onto a screen, it allows users to observe and measure the shape, dimensions, and features of the object with high accuracy. It is widely used in industries and laboratories for precision inspection and measurement tasks.
• A shadow projector works by shining light onto an object, casting its shadow onto a screen or viewing surface. The image formed is magnified, enabling detailed inspection of the object's profile or surface features. The optical system ensures that the image remains undistorted and true to the object's dimensions, which is critical for applications requiring precision.

Advantages:

• Provides high accuracy in imaging and measurement.
• Allows inspection of intricate details that may not be visible to the naked eye.
• Non-contact method—ideal for delicate or sensitive objects.
• Can be used to inspect and measure objects of varying sizes and shapes.

Disadvantages:

• Limited to inspecting surface profiles and dimensions; cannot detect internal flaws.
• Requires proper calibration and alignment for accurate results.
• May not be suitable for analyzing material composition.

Applications:

• Precision measurement in manufacturing industries.
• Inspection of mechanical parts and tools.
• Quality control processes in industrial applications.
• Educational purposes for studying optical projection principles.

Explanation:

Surface Coating Process

• Surface coating is a process in which a protective or functional layer is applied to the surface of a material (substrate) to improve its properties, such as corrosion resistance, wear resistance, appearance, or other functional characteristics. This layer can be applied using various techniques, one of which is hot dipping.

Hot Dipping:

• Hot dipping is a widely used surface coating process in which a metal substrate is immersed into a bath of molten material (usually zinc, aluminum, or tin) to create a protective coating. This process is commonly used for corrosion protection and is widely applied in industries for galvanizing steel and other metals.
• The substrate to be coated is cleaned thoroughly to remove any contaminants, such as grease, oil, or oxides. It is then dipped into a molten bath of the coating material. The molten material adheres to the surface of the substrate and forms a uniform layer. After withdrawal from the molten bath, the coated material is cooled to solidify the coating.

Steps Involved in Hot Dipping:

1. Surface Preparation: This involves cleaning the substrate to remove dirt, grease, and oxides. Common cleaning methods include pickling (acid cleaning), alkaline cleaning, and abrasive cleaning. Proper surface preparation ensures good adhesion of the coating.
2. Hot Dipping: The cleaned substrate is immersed in a molten bath of the coating material. The coating material typically includes metals like zinc (for galvanization), aluminum, or tin.
3. Cooling and Solidification: After dipping, the substrate is withdrawn from the molten bath and allowed to cool. The coating solidifies, forming a durable and protective layer on the surface.

Advantages of Hot Dipping:

• Provides excellent corrosion resistance, especially in steel and iron components.
• Forms a metallurgical bond between the substrate and coating, resulting in high durability.
• Relatively low-cost method for large-scale applications.
• Can be applied to a wide range of materials and shapes.

Applications:

• Galvanization of steel and iron components to protect them from rust and corrosion.
• Coating of electrical components to improve conductivity and resistance to oxidation.
• Used in the construction industry for coated roofing sheets, pipes, and wires.

Additional InformationOption 1: Tumbling

It is a finishing process used to smooth, polish, or deburr the surface of a material. In tumbling, the workpieces are placed in a rotating barrel or vibratory tumbler along with abrasive media. This process is used to improve the surface finish of components but does not apply a coating.

Option 4: Pickling

Pickling is a surface treatment process used to remove impurities, such as oxides, rust, and scale, from the surface of metals. It involves immersing the metal in an acid solution (e.g., hydrochloric acid or sulfuric acid).

Explanation:

Surface Texture Measurement

Definition: Surface texture measurement is a critical aspect in manufacturing and engineering that involves evaluating the surface characteristics of a material or part. The surface texture includes various attributes such as roughness, waviness, and lay, which can significantly affect the performance, aesthetics, and longevity of the part.

Working Principle: To measure surface texture, an instrument known as a profilometer is used. The profilometer traverses across the surface of the workpiece to record the topographical features. The part of the profilometer that makes contact with the workpiece surface is crucial for capturing accurate measurements.

Correct Option Analysis:

The correct option is:

Option 2: a finely pointed stylus

This option correctly identifies the part of the profilometer that makes contact with the workpiece surface. The finely pointed stylus is responsible for tracing the surface profile, detecting and recording the minute variations in texture. This contact method allows for precise measurement of surface roughness and other texture parameters.

Advantages:

• High precision in measuring surface irregularities, providing detailed and accurate surface texture data.
• Capability to measure very small surface features, which is essential for high-precision engineering applications.

Disadvantages:

• The contact nature of the measurement can sometimes cause wear on both the stylus and the workpiece surface.
• Not suitable for very soft or delicate surfaces where the stylus might cause damage.

Applications: Surface texture measurement with a finely pointed stylus is widely used in various industries, including automotive, aerospace, and precision engineering, where high surface quality is critical.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: an electrical pickup

An electrical pickup typically refers to a component used in various electronic instruments to convert physical quantities into electrical signals. While profilometers may use electrical pickups to process the signals generated by the stylus, the electrical pickup itself does not make direct contact with the workpiece surface.

Option 3: a motorised mechanism

A motorised mechanism in a profilometer is responsible for moving the stylus or the workpiece to ensure a consistent and controlled measurement process. However, the motorised mechanism does not make contact with the workpiece surface; it simply facilitates the movement of the stylus.

Option 4: a recording unit

The recording unit in a profilometer is used to capture, process, and display the surface texture data obtained from the stylus. While it is an essential part of the measurement system, it does not make direct contact with the workpiece surface.

Conclusion:

Understanding the components and their functions in a profilometer is crucial for accurate surface texture measurement. The finely pointed stylus is the part that directly interacts with the workpiece surface, making it integral to capturing detailed surface characteristics. This contact method allows for high precision in measurements, though it requires careful handling to avoid damage to both the stylus and the workpiece.

Explanation:

Gas lasers:

• Gas lasers are the most commonly used type of lasers in laser interferometers for metrology applications. The reason for their widespread use lies in their stability, coherence, and ability to produce high-quality beams. Here are some detailed points explaining why gas lasers are preferred:

1. High Stability: Gas lasers, such as the Helium-Neon (He-Ne) laser, are known for their high frequency and amplitude stability. This is crucial in metrology applications where precise and accurate measurements are required. The stability ensures that the laser's output remains consistent over time, reducing the chances of measurement errors.

2. Long Coherence Length: Coherence length is a measure of how monochromatic (single-wavelength) the laser light is. Gas lasers typically have a long coherence length, which is essential for interferometry. A longer coherence length means that the laser light can maintain its phase relationship over longer distances, which is necessary for producing clear and accurate interference patterns in interferometry.

3. High Beam Quality: Gas lasers produce high-quality beams with low divergence and minimal beam distortion. This high beam quality ensures that the laser light can be precisely directed and focused, which is important for accurate interferometric measurements.

4. Narrow Linewidth: Gas lasers have a very narrow linewidth, meaning they emit light at a very precise wavelength. This narrow linewidth is important for high-resolution measurements in metrology, as it reduces the uncertainty in the measurement of distances.

5. Reliability and Longevity: Gas lasers are known for their reliability and long operational life. This makes them suitable for continuous and long-term use in metrology applications, where consistent performance over time is essential.

Explanation:

Function of Coolants in Metal Cutting or Machining Operations

Definition: Coolants are essential fluids used in metal cutting or machining operations to manage the heat generated during these processes. The primary function of coolants is to enhance the efficiency of the cutting operation by maintaining the temperature within manageable limits, ensuring the longevity of the tool, and improving the quality of the finished product.

Working Principle: During metal cutting or machining, friction between the tool and the workpiece generates significant heat. Excessive heat can lead to tool wear, deformation of the workpiece, and poor surface finish. Coolants act by absorbing this heat and carrying it away from the cutting zone, reducing the temperature of both the tool and the workpiece. This cooling effect is crucial for maintaining the integrity of the tool and the quality of the machining process.

Benefits of Using Coolants:

• Decreased Adhesion Between Chip and Tool: Coolants reduce the adhesion between the chip and the tool, which is the primary function of coolants in metal cutting. This reduction in adhesion minimizes the chances of built-up edge (BUE) formation on the tool, resulting in a smoother surface finish and better dimensional accuracy of the workpiece.
• Reduced Tool Wear: By effectively managing the heat generated during cutting, coolants reduce the wear and tear on cutting tools. This leads to longer tool life and fewer tool replacements, contributing to reduced operational costs.
• Improved Surface Finish: The cooling action of coolants helps in achieving a better surface finish on the workpiece. This is because lower temperatures reduce the chances of thermal deformation and ensure cleaner cuts.
• Enhanced Machinability: Coolants help in reducing cutting forces, making the machining process smoother and more efficient. This improved machinability allows for higher cutting speeds and feeds, increasing productivity.
• Lubrication: Besides cooling, coolants also provide lubrication between the tool and the workpiece. This lubrication reduces friction, further contributing to the reduction in heat generation and tool wear.

Applications: Coolants are widely used in various machining operations such as turning, milling, drilling, and grinding. They are indispensable in industries where precision and surface quality are critical, such as aerospace, automotive, and manufacturing sectors.

GIven:

Length of the cylinder (h) = 1.4 m = 140 cm, External radius of cylinder, R = 9 cm and internal radius of cylinder = r cm

Concept:

Volume of solid cylinder, \(V_s=\pi R^2h\)

Volume of hollow cylinder, \(V_h=\pi (R^2-r^2)h\)

Calculation:

Volume of hollow cylinder = \(V_h= \pi (R^2-r^2)h\)

\(\Rightarrow 7480=\frac{22}{7} \times (9^2-r^2) \times 140\)

\(\Rightarrow(81-r^2) = 17\)

⇒ r = 8 cm

The train crosses = 200 + 400 = 600 m

∴ Speed of the train = 600/40 = 15 m/s = 15 × (18/5) km/hr = 54 km/hr

The correct answer is Cohesive force between molecules.

Key Points

• Surface tension: Surface tension is a measure of the cohesive forces between liquid molecules present at the surface.​
• Molecules at the surface of a liquid are partly exposed to the surrounding. The molecules at the liquid-air interface experience fewer interactions and have more energy to escape to the surrounding.
• Therefore, energy is required to bring molecules from the bulk of the liquid to the surface. The stronger the intermolecular interaction, the greater is the energy required to increase the surface area of a liquid.
• This energy is called the surface energy and is related to surface tension as

• ​Surface tension =\(\frac{ surface \:energy}{area}\)

The correct answer is Sonorous.

Key Points

• A sonorous is a substance which is capable of producing sound. Metals are generally sonorous they produce sound on being struck or hit by something. 
• The physical property of the metal produced a ringing sound when it strikes on a hard surface is called sonority, hence the temple bells or school bells are made up of sonorous metals.

Additional Information

• Ductile is a material that is able to draw out into thin wire and deformed without losing its toughness. 
• Malleable is a material able to be pressed or hammered into shape without cracking or breaking.

⇒ Required sum = 2 + 4 + 6 + 8 + ……. + 36

⇒ Required sum = 2(1 + 2 + 3 + …… + 18)

We know that,

Sum of first n natural numbers = n(n + 1)/2

⇒ Required sum = 2 × n × (n + 1)/2      (where n = 18)

Explanation:

Calculation:

Let an equal number of 1 rupee, 2 rupee, and 5 rupee coins be x

So, (1 × x + 2 × x + 5 × x) = 184

⇒ 8x = 184

⇒ x = 23

The correct answer is blue.

Key Points

• Gold and copper happen to absorb blue and violet light, leaving yellow light in the spectrum.
• So gold and copper are yellowish in colour.
• The only two non-silvery metals in the world are gold and copper.
• A metal is defined as an element that readily forms positive ions (cations) and has metallic bonds.
• These elements have electrons that are loosely held to the atoms, and will readily transfer them. 
• Most metals' electrons reflect all colours equally which are in the visible spectrum of light.
• So those metals appear as white silver.

Explanation:

Explanation:

• A fire extinguisher, flame extinguisher or simply extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations.
• It is not intended for use on and out off control fire. 
• Many types of fire extinguishers are available with different extinguishing 'agents' to deal with different classes of fires. 

Carbon dioxide (CO2):

• This type is easily distinguished by the distinctively shaped discharge horn.
• Suitable for class B fires
• Best suited where contamination by deposits must be avoided.
• Not generally effective in the open air.
• If the nozzle gets extremely cold, then it is dangerous to use that Extinguisher.
• CO₂ extinguishers have Black labels on the top of the cylinder

Water-filled extinguishers 

• There are two methods of operation.
  1. Gas cartridge type
  2. Stored pressure type
• Water-filled extinguishers have Red labels on the top of the cylinder

Foam extinguishers:

• These may be of stored pressure or gas cartridge types.
• Foam extinguishers are most suitable for:
  1. flammable liquid fires
  2. running liquid fires
• Must not be used where electrical equipment is involved.
• Foam extinguishers have Cream labels on the top of the cylinder

Dry powder extinguishers:

• Extinguishers fitted with dry powder may be of the gas cartridge or stored pressure type.
• The main distinguishing feature is the fork-shaped nozzle.
• Powders have been developed to deal with class D fires. 
• Dry powder extinguishers have Blue labels on the top of the cylinder

Halon extinguishers:

• These extinguishers may be filled with carbon tetrachloride (CTC) and bromochlorodifluoro methane (BCF).
• They may be of the either gas cartridge or stored pressure type.
• They are more effective in extinguishing small fires involving pouring liquids.
• These extinguishers are particularly suitable and safe to use on electrical equipment as the chemicals are electrically non-conductive.