GATE EC question library

​​​​A causal and stable $\text{LTI}$ system with impulse response $h(t)$ produces an output $y(t)$ for an input signal $x(t)$. A signal $x(0.5 t)$ is applied to another causal and stable $\text{LTI}$ system with impulse response $h(0.5 t)$. The resulting output is $\_\_\_\_\_\_\_$.

​​​​For non-degenerately doped n-type silicon, which one of the following plots represents the temperature $(T)$ dependence of free electron concentration $(n)$ ?

​In the circuit shown, the $n: 1$ step-down transformer and the diodes are ideal. The diodes have no voltage drop in forward biased condition. If the input voltage (in Volts) is $V_{s}(t)=10 \sin \omega t$ and the average value of load voltage $V_{L}(t)$ (in Volts) is $2.5 / \pi$, the value of $n$ is $\_\_\_\_\_\_\_$.

​​​​​For a causal discrete-time LTI system with transfer function $$H(z)=\frac{2 z^{2}+3}{\left(z+\frac{1}{3}\right)\left(z-\frac{1}{3}\right)}$$ which of the following statements is/are true?

​​​​​Let $\rho(x, y, z, t)$ and $u(x, y, z, t)$ represent density and velocity, respectively, at a point $(x, y, z)$ and time $t$. Assume $\frac{\partial \rho}{\partial t}$ is continuous. Let $V$ be an arbitrary volume in space enclosed by the closed surface $S$ and $\hat{n}$ be the outward unit normal of $S$ Which of the following …

​​​The free electron concentration profile $n(x)$ in a doped semiconductor at equilibrium is shown in the figure, where the points $\mathrm{A}, \mathrm{B}$, and $\mathrm{C}$ mark three different positions. Which of the following statements is/are true?

A machine has a $32$-bit architecture with $1$-word long instructions. It has $24$ registers and supports an instruction set of size $40$. Each instruction has five distinct fields, namely opcode, two source register identifiers, one destination register identifier, and an immediate value. Assuming that the immediate operand is an unsigned integer, …

An amplitude modulator has output (in Volts) $$s(t)=A \cos (400 \pi t)+B \cos (360 \pi t)+B \cos (440 \pi t) .$$ The carrier power normalized to $1 \Omega$ resistance is $50$ Watts. The ratio of the total sideband power to the total power is $1 / 9$. The value of $\text{B}$ (in Volts, rounded off to two decimal places) is $\_\_\_\_\_\_\_$.

In a number system of base $r$, the equation $x^{2}-12 x+37=0$ has $x=8$ as one of its solutions. The value of $r$ is $\_\_\_\_\_\_\_$.

Let $\mathbb{R}$ and $\mathbb{R}^{3}$ denote the set of real numbers and the three dimensional vector space over it, respectively. The value of $\alpha$ for which the set of vectors …

In the given circuit, the current $I_{x}$ (in $m A$ ) is $\_\_\_\_\_\_\_\_$.

In the circuit given below, the switch $\text{S}$ was kept open for a sufficiently long time and is closed at time $t=0$. The time constant (in seconds) of the circuit for $t>0$ is $\_\_\_\_\_\_$.

Suppose $\text{X}$ and $\text{Y}$ are independent and identically distributed random variables that are distributed uniformly in the interval $[0,1]$. The probability that $\text{X} \geq \text{Y}$ is $\_\_\_\_\_\_$.

A source transmits symbols from an alphabet of size $16$. The value of maximum achievable entropy (in bits) is $\_\_\_\_\_\_$.

As shown in the circuit, the initial voltage across the capacitor is $10 \mathrm{~V}$, with the switch being open. The switch is then closed at $t=0$. The total energy dissipated in the ideal Zener diode $\left(V_{Z}=5 \mathrm{~V}\right)$ after the switch is closed (in $\mathrm{mJ}$, rounded off to three decimal places) is $\_\_\_\_\_\_$.

​​​​​Consider the Earth to be a perfect sphere of radius $\text{R}$. Then the surface area of the region, enclosed by the $60^{\circ} \mathrm{N}$ latitude circle, that contains the north pole in its interior is $\_\_\_\_\_\_$.

​​​​​Consider a unity negative feedback control system with forward path gain $G(s)=\frac{K}{(s+1)(s+2)(s+3)}$ as shown. The impulse response of the closed-loop system decays faster than $e^{-t}$ if $\_\_\_\_\_\_$.

​​​​​A satellite attitude control system, as shown below, has a plant with transfer function $G(s)=\frac{1}{s^{2}}$ cascaded with a compensator $C(s)=\frac{K(s+\alpha)}{s+4}$, where $K$ and $\alpha$ are positive real constants. In order for the closed-loop system to have poles at $-1 \pm j \sqrt{3}$, the value of $\alpha$ must be …

A uniform plane wave with electric field $\vec{E}(x)=A_{y} \hat{a}_{y} e^{-j \frac{2 \pi x}{3}} \mathrm{~V} / \mathrm{m}$ is travelling in the air (relative permittivity, $\epsilon_{r}=1$ and relative permeability, $\mu_{r}=1$ ) in the $+x$ direction ( $A_{y}$ is a positive constant, $\hat{a}_{y}$ is the unit vector along the $y$ axis). It is …

​​​​​A $4$-bit priority encoder has inputs $D_{3}, D_{2}, D_{1}$, and $D_{0}$ in descending order of priority. The two-bit output $A B$ is generated as $00,01,10$, and 11 corresponding to inputs $D_{3}, D_{2}, D_{1}$, and $D_{0}$, respectively. The Boolean expression of the output bit $B$ is $\_\_\_\_\_\_\_$.