GATE EC question library

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 $\_\_\_\_\_\_\_$.

​​​​​The propagation delay of the $2 \times 1$ MUX shown in the circuit is $10 \mathrm{~ns}$. Consider the propagation delay of the inverter as $0 \mathrm{~ns}$. If $\text{S}$ is set to $1$ then the output $\text{Y}$ is $\_\_\_\_\_\_$.

​​​​​The sequence of states $\left(Q_{1} Q_{0}\right)$ of the given synchronous sequential circuit is - $\_\_\_\_\_\_\_$.

​​​​​Let $z$ be a complex variable. If $f(z)=\frac{\sin (\pi z)}{z^{2}(z-2)}$ and $C$ is the circle in the complex plane with $|z|=3$ then $\oint_{C} f(z) d z$ is $\_\_\_\_\_\_$.

Consider two continuous time signals $x(t)$ and $y(t)$ as shown below If $X(f)$ denotes the Fourier transform of $x(t)$, then the Fourier transform of $y(t)$ is $\_\_\_\_\_\_$.

​​​​​A source transmits a symbol $s$, taken from $\{-4,0,4\}$ with equal probability, over an additive white Gaussian noise channel. The received noisy symbol $r$ is given by $r=s+w$, where the noise $w$ is zero mean with variance 4 and is independent of $s$. Using $Q(x)=\frac{1}{\sqrt{2 \pi}} \int_{x}^{\infty} e^{\frac{-t^{2}}{2}} d t$, the …

​​​​​A full scale sinusoidal signal is applied to a $10$ -bit $\mathrm{ADC}$. The fundamental signal component in the $\mathrm{ADC}$ output has a normalized power of $1 \mathrm{~W}$, and the total noise and distortion normalized power is $10 \mu \mathrm{W}$. The effective number of bits (rounded off to the nearest integer) of the $\mathrm{ADC}$ …

​​​​​The information bit sequence $\{111010101\}$ is to be transmitted by encoding with Cyclic Redundancy Check $4$ (CRC-$4$) code, for which the generator polynomial is $C(x)=x^{4}+x+1$. The encoded sequence of bits is $\_\_\_\_\_\_\_$.

​​​​A continuous time signal $x(t)=2 \cos (8 \pi t+\pi / 3)$ is sampled at a rate of $15 \mathrm{~Hz}$. The sampled signal $x_{s}(t)$ when passed through an LTI system with impulse response $$h(t)=\left(\frac{\sin 2 \pi t}{\pi t}\right) \cos (38 \pi t-\pi / 2)$$ produces an output $x_{o}(t)$. The expression for $x_{o}(t)$ is $\_\_\_\_\_$.

​​​​​The opamps in the circuit shown are ideal, but have saturation voltages of $\pm 10 \mathrm{~V}$. Assume that the initial inductor current is $0 \mathrm{~A}$. The input voltage $\left(\mathrm{V}_{\mathrm{i}}\right)$ is a triangular signal with peak voltages of $\pm 2 \mathrm{~V}$ and time period of $8 \mu \mathrm{s}$. Which one of the following …

In the circuit below, the opamp is ideal. If the circuit is to show sustained oscillations, the respective values of $R_{1}$ and the corresponding frequency of oscillation are