Electronics and Communication Gate 2014 Set-4 Questions with Answer

Ques 27 GATE 2014 SET-4

If E = −(2y³ − 3yz²)x̂ − (6xy² − 3xz²)ŷ + (6xyz)ẑ is the electric field in a source free region, a valid expression for the electrostatic potential is

xy³ − yz²

2xy³ − xyz²

y³ + xyz²

2xy³ − 3xyz²

(b) is the correct answer.

Ques 28 GATE 2014 SET-4

At T = 300 K, the band gap and the intrinsic carrier concentration of GaAs are 1.42 eV and 10⁶ cm⁻³, respectively. In order to generate electron hole pairs in GaAs, which one of the wavelength (λ_C) ranges of incident radiation, is most suitable? (Given that: Plank's constant is 6.62 × 10⁻³⁴ J-s, velocity of light is 3 × 10¹⁰ cm/s and charge of electron is 1.6 × 10⁻¹⁹ C)

0.42 μm < λ_C < 0.87 μm

0.87 μm < λ_C < 1.42 μm

1.42 μm < λ_C < 1.62 μm

1.62 μm < λ_C < 6.62 μm

(a) is the correct answer.

Ques 29 GATE 2014 SET-4

In the figure, ln(ρ_i) is plotted as a function of 1/T, where ρ_i is the intrinsic resistivity of silicon, T is the temperature, and the plot is almost linear.

The slope of the line can be used to estimate

band gap energy of silicon (E_g)

sum of electron and hole mobility in silicon (μ_n + μ_p)

reciprocal of the sum of electron and hole mobility in silicon (μ_n + μ_p)⁻¹

intrinsic carrier concentration of silicon (n_i)

(a) is the correct answer.

Ques 30 GATE 2014 SET-4

The cut-off wavelength (in μm) of light that can be used for intrinsic excitation of a semiconductor material of bandgap E_g = 1.1 eV is ________

(1.13) is the correct answer.

Ques 31 GATE 2014 SET-4

Consider a silicon sample doped with N_D = 1×10¹⁵/cm³ donor atoms. Assume that the intrinsic carrier concentration n_i = 1.5×10¹⁰/cm³. If the sample is additionally doped with N_A = 1×10¹⁸/cm³ acceptor atoms, the approximate number of electrons/cm³ in the sample, at T=300 K, will be ______.

(225) is the correct answer.

Ques 32 GATE 2014 SET-4

Consider two BJTs biased at the same collector current with area A₁ = 0.2 μm × 0.2 μm and A₂ = 300 μm × 300 μm. Assuming that all other device parameters are identical, kT/q = 26 mV, the intrinsic carrier concentration is 1 × 10¹⁰ cm⁻³, and q = 1.6 × 10⁻¹⁹ C, the difference between the base-emitter voltages (in mV) of the two BJTs (i.e., V_BE1 – V_BE2) is _____.

(380) is the correct answer.

Ques 33 GATE 2014 SET-4

An N-type semiconductor having uniform doping is biased as shown in the figure.

If E_C is the lowest energy level of the conduction band, E_V is the highest energy level of the valance band and E_F is the Fermi level, which one of the following represents the energy band diagram for the biased N-type semiconductor?

(d) is the correct answer.

Ques 34 GATE 2014 SET-4

The series ∑_n=0^∞ (1/n!) converges to

2 ln 2

√2

(d) is the correct answer.

Ques 35 GATE 2014 SET-4

The magnitude of the gradient for the function f(x, y, z) = x² + 3y² + z³ at the point (1,1,1) is _________.

(7) is the correct answer.

Ques 36 GATE 2014 SET-4

Let X be a zero mean unit variance Gaussian random variable. E[|X|] is equal to _____

(0.8) is the correct answer.

Ques 37 GATE 2014 SET-4

If a and b are constants, the most general solution of the differential equation
d²x/dt² + 2(dx/dt) + x = 0 is

ae^−t

ae^−t + bte^−t

ae^t + bte^−t

ae^−2t

(b) is the correct answer.

Ques 38 GATE 2014 SET-4

The directional derivative of f(x, y) = x² + xy at (1, 1) in the direction of the unit vector at an angle of π/4 with y-axis, is given by ______.

(3) is the correct answer.

Ques 39 GATE 2014 SET-4

With initial values y(0) = y′(0) = 1, the solution of the differential equation
d²y/dx² + 4(dy/dx) + 4y = 0
at x = 1 is _____.

(0.54) is the correct answer.

1 2 3 4 5

Total Unique Visitors

Loading......

Electronics & Communication Gate Yearwise

Electronics and Communication Gate 2014 Set-4 Questions with Answer

Question Options

Sign in to ExamPrev