Detecting internal defects in metal castings is crucial to ensure the structural integrity and performance of the casting. Various non-destructive testing (NDT) techniques are available for this purpose. Let's analyze the given options:
Step 1: Analysis of the options
- Option (A): "Ultrasonic inspection" - Correct: Ultrasonic inspection uses high-frequency sound waves to detect internal defects. It works by sending sound waves through the material and measuring the time taken for the waves to return. Any internal defect (such as cracks or voids) causes a reflection of these sound waves, which helps in detecting the defect. Hence, this technique is effective for detecting internal defects in metal castings.
- Option (B): "Liquid (or dye) penetrant inspection" - Incorrect: Liquid penetrant inspection is generally used for detecting surface defects rather than internal defects. It involves applying a liquid dye or fluorescent solution to the surface of the material. It is not effective for detecting internal defects.
- Option (C): "Gamma-ray radiography" - Correct: Gamma-ray radiography is a non-destructive testing technique that uses gamma rays to penetrate the material and produce an image of the internal structure. This technique can detect internal defects such as cracks, voids, and inclusions, making it suitable for inspecting metal castings.
- Option (D): "X-ray radiography" - Correct: X-ray radiography is similar to gamma-ray radiography, but it uses X-rays instead of gamma rays. It is an effective method for detecting internal defects such as cracks, porosity, and voids in metal castings. It provides a detailed image of the internal structure of the material.
Step 2: Conclusion The correct techniques for detecting internal defects in metal castings are Option A, Option C, and Option D. Ultrasonic inspection, gamma-ray radiography, and X-ray radiography are all effective methods for identifying internal flaws in the material.
Two randomly oriented polycrystalline copper samples with average grain sizes of 10 $\mu$m (Sample A) and 100 $\mu$m (Sample B) were tested at room temperature.
Given: $E_A$ = Young's modulus of Sample A $E_B$ = Young's modulus of Sample B $Y_{SA}$ = Yield strength of Sample A $Y_{SB}$ = Yield strength of Sample B
Which one of the following statements is CORRECT?
Match the following elements in Column I with their respective ores in Column II.

Match the casting defects in Column I with the characteristic features in Column II.

Despite his initial hesitation, Rehman’s ____________ to contribute to the success of the project never wavered.
Select the most appropriate option to complete the above sentence.
Bird : Nest :: Bee : __________
Select the correct option to complete the analogy.
The paper as shown in the figure is folded to make a cube where each square corresponds to a particular face of the cube. Which one of the following options correctly represents the cube? Note: The figures shown are representative.
