Assertion (A): A coaxial line is a non-radiating transmission line. Reason (R): In a coaxial line, the electric and magnetic fields are confined to the region between the concentric conductors. Which statement is correct?
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ABoth A and R are correct, and R is the correct explanation of A
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BBoth A and R are correct, but R is not the correct explanation of A
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CA is correct but R is wrong
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DA is wrong but R is correct
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EBoth A and R are wrong
Answer
Correct Answer: Both A and R are correct, and R is the correct explanation of A
Explanation
Introduction / Context:Coaxial transmission lines are widely used in RF applications because they confine electromagnetic fields and prevent radiation losses. The assertion-reason type question tests the understanding of why coaxial lines do not radiate.
Given Data / Assumptions:
- Structure: inner and outer concentric conductors.
- Fields confined to dielectric between conductors.
Concept / Approach:
The fields in coaxial geometry cancel outside the line. The outer conductor shields the fields, confining them to the dielectric region. This explains why coaxial lines are non-radiating.
Step-by-Step Solution:
Assertion A: coaxial line is non-radiating → true.Reason R: fields confined between conductors → true.Link: confinement is exactly why no external radiation occurs.Verification / Alternative check:
Coaxial cable is preferred for shielding-sensitive RF signals precisely for this reason.
Why Other Options Are Wrong:
- Option B: R is indeed the correct explanation.
- Option C: R is not wrong.
- Option D: A is not wrong.
- Option E: Both are correct.
Common Pitfalls:
Confusing coaxial with two-wire lines that radiate due to unconfined fields.
Final Answer:
Both A and R are correct, and R is the correct explanation of A