Electromagnetic theory miscellaneous
- In the infinite plane y = 6 m there exists a uniform surface charge density of
1 ∏ 600
μ c/m2. The associated electric field strength is—
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The associated electric field strength
1 = 1 × 10−6 × 1 2ε0 600π 2 × 8.85 × 10−12
= 30 kV/mCorrect Option: C
The associated electric field strength
1 = 1 × 10−6 × 1 2ε0 600π 2 × 8.85 × 10−12
= 30 kV/m
- The electric field strength at a distance point P due to a point charge +q located on the origins is 100 µ V/m if the point charge is now enclosed by a perfectly conducting metal sheet sphere whose centre is at origin then the electric field strength at the point P outside the sphere becomes—
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Charge +q induces negative charge inside the sphere and positive charge on the outside of sphere. If the sphere is enclosed by a Gaussian sphere the field strength E will be given by Gauss's law
E = 1 Q 4πε0 R2
where R is radius of sphere and Q is total charge. This is same although the charge is present at the origin of sphere. Therefore + 100 µ V/m.Correct Option: B
Charge +q induces negative charge inside the sphere and positive charge on the outside of sphere. If the sphere is enclosed by a Gaussian sphere the field strength E will be given by Gauss's law
E = 1 Q 4πε0 R2
where R is radius of sphere and Q is total charge. This is same although the charge is present at the origin of sphere. Therefore + 100 µ V/m.
- For a short wave radio link between two stations via the ionosphere. The ratio of the maximum usable frequency to the critical frequency—
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Since we know that fmuf = fc sec i
so,fmuf = sec i > 1 fc
Correct Option: B
Since we know that fmuf = fc sec i
so,fmuf = sec i > 1 fc
- A beam antenna consists of a dipole one reflector and one director. The velocity factor is 0.90 and antenna is to be cut for a frequency of 150 MHz. The length of the dipole will be—
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By calculation as follows
λ = C velocity factor × f λ = 3 ×108 0.9 × 150 × 106
= 1.8Now effective length of dipole = 1 ⇒ 1.8 = 0.9 2 2 Correct Option: C
By calculation as follows
λ = C velocity factor × f λ = 3 ×108 0.9 × 150 × 106
= 1.8Now effective length of dipole = 1 ⇒ 1.8 = 0.9 2 2
- Input impedance for the given line is—
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Graph shows clearly that shorted stub of given length is of capacitive type.
Correct Option: B
Graph shows clearly that shorted stub of given length is of capacitive type.