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GATE EC 2018 Exam: Electromagnetics Quiz 5
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Question 1
If the distance of 100 W lamp is increased from a photocell, the sauration current I in the photocell varies with the distance d as
Question 2
Which of the following rays is emitted by a human body?
Question 3
Two light rays having the same wavelength in vacuum are in phase initially. The, the first ray travels a path L1 through a medium of refractive index μ1 while the second ray travels a path L2 through a medium of refractive index μ2. The two waves are then combined to observe interference. The phase difference between the two waves is
Question 4
If the velocity of light in vacuum is 3 × 108 ms–1, the time taken (in nanosecond) to travel through a glass plate of thickness 10 cm and refractive index 1.5 is
Question 5
The permittivity of water at optical frequencies is 1.75εo .It is found that an isotropic light source at a distance d under-water forms an illuminated circular area of radius 5m, as shown in the figure. The critical angle is θc.
The value of d (in meter) is _____
Question 6
For an 8 feet (2.4 m) parabolic disk antenna operating at 4 GHz, the minimum distance required for far field measurement is closest to
Question 7
The internal dimensions of a coaxial capacitor are a = 1cm, b = 3cm, c = 30cm. The capacitor contains a homogeneous material inside with 
= 10-10 F/m, µ = 10-6 H/m, σ = 10-4 mho/m. What will be the quality factor of the capacitor if
?
= 10-10 F/m, µ = 10-6 H/m, σ = 10-4 mho/m. What will be the quality factor of the capacitor if ?Question 8
A radar operating at 5 GHz uses a common antenna for transmission and reception. The antenna has a gain of 150 and is aligned for maximum directional radiation and reception to a target 1 km away having radar cross-section of 
. If it transmits 100 kW, then the received power (in 
)is _____.
. If it transmits 100 kW, then the received power (in )is _____. Question 9
The de Broglie wavelength of an electron moving with a velocity c/2 (C = velocity of light in vacuum) is equal to the wavelength of a photon. The ratio of the kinetic energies of electron and photon is
Question 10
A photon of wavelength 300 nm interacts with a stationary hydrogen atom in ground state. During the interaction, whole energy of the photon is transferred to the election of the atom. State which possibility is correct. (consider, Planck constant = 4 x 10–15 eVs, velocity of light = 3 x 108 m/s, ionization energy of hydrogen = 13.6 eV)
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