Electromagnetic theory miscellaneous
- The input impedance of a loss-less transmission line is 100 ohms when terminated in a short-circuit, and 64 ohms when terminated in an open circuit. The characteristic impedance of the line is—
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Z0 = √Zin·ZL = √100 × 64 = 80 ohm
Correct Option: A
Z0 = √Zin·ZL = √100 × 64 = 80 ohm
- A rectangular loop in the x-z plane bounded by the lines
x = 0, x = a, z = 0 and z = b, in a time-varying magnetic field given by
B = B0 cos ωt ay
where B0 is a constant, ω is the angular frequency and – ay is the unit vector in the y-direction. The emf induced in the loop is given by—
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B = B0 cos ωt + iy
Again | e (t) | = d/ dt (ab B0 cos ωt)
= ab B0 ω sin ωtCorrect Option: B
B = B0 cos ωt + iy
Again | e (t) | = d/ dt (ab B0 cos ωt)
= ab B0 ω sin ωt
- Kirchhoff's current law for direct currents is implicit in the expression—
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∫s J.ds implies that the net current coming out of a closed surface is zero; which is the KCL for direct current.
Correct Option: B
∫s J.ds implies that the net current coming out of a closed surface is zero; which is the KCL for direct current.
- A circular loop has its radius increasing at a rate of 2 m/s. The loop is placed perpendicular to a constant magnetic field 0.1 Wb/m2. When the radius of the loop is 2 m, the emf induced in the loop will be—
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The area of the loop is A = π r2
Flux linking the area, φ = B × πr2Induced emf, e(t) = dφ dt
e (t) = d/ dt {B πr2} = B π 2r (dr/ dt)
or e (t) = 0.1 × π × 2 × 2 × 2 = 0.8 πV
Correct Option: A
The area of the loop is A = π r2
Flux linking the area, φ = B × πr2Induced emf, e(t) = dφ dt
e (t) = d/ dt {B πr2} = B π 2r (dr/ dt)
or e (t) = 0.1 × π × 2 × 2 × 2 = 0.8 πV
- Given that L = 1 µH/m, C = 11.11 pf/m the group delay time is—
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Group delay time td = β/ ω
β = ω√LCCorrect Option: B
Group delay time td = β/ ω
β = ω√LC