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Electronics and Communication Engineering - Exam Questions Papers - Discussion

Discussion Forum : Exam Questions Papers - Exam Paper 2 (Q.No. 50)
Exam Questions Papers
50.

Assertion (A): Conductors do not permit propagation of waves more than a short distance into the conductor at microwave frequencies.

Reason (R): The relaxation time constant for conductors is much small than the period of centimetric EM wave.

Both (A) and (R) are true and (R) is the correct explanation of (A)
Both (A) and (R) are true but (R) is not the correct explanation of (A)
(A) is true but (R) is false
(A) is false but (R) is true
Answer: Option
Explanation:

Depth of penetration = , where = relaxation time.

δ would be small, if σ is large, which itself depends upon relaxation time.

t for conductors is of the order of 10-14 s, for λ = 3 x 10-2 cm

∴ period of centimetric EM waves

=

Therefore, even though t is much smaller than period of centimetric waves but it is not the correct reason for the assertion given.

Discussion:
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