The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?

Analysis

The question asks for the specific radioisotope used in industrial radiography. Industrial radiography is a non-destructive testing method used to inspect the internal structure of materials, such as metal welds and castings, to detect cracks, voids, or other structural defects.

Concept Explanation

Radioisotopes are unstable isotopes of elements that emit radiation (alpha, beta, or gamma rays) as they decay. In industrial radiography, we require a source that emits gamma rays because they have high penetrating power, allowing them to pass through thick metal objects and expose photographic film on the other side.

• Carbon-14: Primarily used in radiocarbon dating of organic materials (archaeology).
• Phosphorus-32: Used in medical and agricultural research as a tracer to study plant metabolism or treat certain blood disorders.
• Cobalt-60: A powerful emitter of gamma rays. Its high energy and long half-life make it the standard choice for industrial radiography to inspect heavy-duty welds and steel castings.
• Iodine-131: Primarily used in medicine for diagnosing and treating thyroid conditions.

Step-by-Step Solution

1. Identify the requirement: We need a radioisotope capable of penetrating dense materials like steel welds.
2. Evaluate the options: • A (Carbon-14) is a weak beta emitter, unsuitable for penetrating metal. • B (Phosphorus-32) is also a beta emitter, unsuitable for industrial imaging. • C (Cobalt-60) is a well-known gamma-ray source used extensively in industry for "taking X-rays" of metal parts. • D (Iodine-131) is a gamma emitter, but it is specifically used for biological/medical applications, not industrial structural testing.
3. Conclusion: Cobalt-60 is the correct isotope for industrial radiography.

Exam Tip

When you see questions about radioisotopes, remember this "cheat sheet":

• Carbon-14: Dating old things (fossils).
• Cobalt-60: Checking metal welds (industrial).
• Iodine-131: Thyroid treatment (medical).
• Phosphorus-32: Plant/Blood research (tracer).