Electromagnetic theory miscellaneous
- Match the different ionospheric layers with their virtual heights
A. A D layer 1. 180 km B. E layer 2. 25-400 km C. F1 layer 3. 70 km D.F2 layer 4. 110 km
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NA
Correct Option: D
NA
- White noise is that signal whose frequency spectrum—
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White noise is a signal whose frequency spectrum has flat spectral density.
Correct Option: B
White noise is a signal whose frequency spectrum has flat spectral density.
- The spectral density of pink noise varies as—
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The spectral density of pink noise varies as 1/f2.
Correct Option: A
The spectral density of pink noise varies as 1/f2.
- When an iron core is placed between the poles of a permanent magnet as shown in figure below, the magnetic field pattern is—
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Figure (C) is the best answer.
Correct Option: C
Figure (C) is the best answer.
- For an infinite linear current, four loops are shown in the given figure. The magnetic flux should be the maximum through the loop number—
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All the loops have equal areas. B at any distance r from the wire is k/ r. For any rectangular loop of height h (in the direction of the wire) and width w (⊥ the wire), the flux φ is
a + w khdr ∞ = kh ln a + w a r a
where a is the distance of the near side from the wire.
Thus,for 1, φ1 = k l ln a + 1 a for 2, φ2 = k 2l ln a + 1/2 a for 3, φ3 = 1 k2l ln a + 1/4 + 1 2 a + 1/4 for 4, φ4 = kl ln a + 2 l a φ1 = kl ln 1 + 1 ,φ2 = 2kl ln 1 + 1 a a φ3 = kl ln 1 + 1 ,φ4 = 1 kl ln 1 + 2 l a + 1/4 2 a
The long terms do not change by significant amount. Thus, φ2 should be of highest value.
Hence alternative (B) is the correct choice.
Correct Option: B
All the loops have equal areas. B at any distance r from the wire is k/ r. For any rectangular loop of height h (in the direction of the wire) and width w (⊥ the wire), the flux φ is
a + w khdr ∞ = kh ln a + w a r a
where a is the distance of the near side from the wire.
Thus,for 1, φ1 = k l ln a + 1 a for 2, φ2 = k 2l ln a + 1/2 a for 3, φ3 = 1 k2l ln a + 1/4 + 1 2 a + 1/4 for 4, φ4 = kl ln a + 2 l a φ1 = kl ln 1 + 1 ,φ2 = 2kl ln 1 + 1 a a φ3 = kl ln 1 + 1 ,φ4 = 1 kl ln 1 + 2 l a + 1/4 2 a
The long terms do not change by significant amount. Thus, φ2 should be of highest value.
Hence alternative (B) is the correct choice.