GATE EC question library

Which one of the following graphs shows the Shannon capacity (channel capacity) in bits of a memoryless binary symmetric channel with crossover probability $p$ ?

Consider the random process $X(t)=U+Vt,$ Where $U$ is a zero-mean Gaussian random variable and V is a random variable uniformly distributed between $0$ and $2$. Assume that $U$ and $V$ are statistically independent. The mean value of the random process at $t = 2$ is ________

A sinusoidal message signal is converted to a PCM signal using a uniform quantizer. The required signal-to-quantization noise ratio (SQNR) at the output of the quantizer is $40$ dB. The minimum number of bits per sample needed to achieve the desired SQNR is __________

Two conducting spheres $S1$ and $S2$ of radii $a$ and $b$ ($b>a$) respectively, are placed far apart and connected by a long, thin conducting wire, as shown in the figure. For some charge placed on this structure, the potential and surface electric field on $S1$ are $V_a$ and $E_a$ and that on S2 are $V_b$ and $E_b$, respectively. …

A two-wire transmission line terminates in a television set. The VSWR measured on the line is $5.8$. The percentage of power that is reflected from the television set is _________

The values of the integrals $$\int_{0}^{1}\left ( \int_{0}^{1}\frac{x-y}{(x+y)^3}dy \right )dx$$ and $$\int_{0}^{1}\left ( \int_{0}^{1}\frac{x-y}{(x+y)^3}dx \right )dy$$ are

An integral $I$ over a counterclockwise circle $\textbf{C}$ is given by $$I=\oint _c \frac{z^2-1}{z^2+1} e^z dz.$$ If $\textbf{C}$ is defined as$\mid z \mid=3$ , then the value of $I$ is

If the vector function $\overrightarrow{F}=\widehat{a_x}(3y-k_1z)+\widehat{a_y}(k_2x-2z)-\widehat{a_z}(k_3y+z)$ is irrotational, then the values of the constants $k_1$,$k_2$ and $k_3$, respectively, are

Passengers try repeatedly to get a seat reservation in any train running between two stations until they are successful. If there is $40 \%$ chance of getting reservation in any attempt by a passenger, then the average number of attempts that passengers need to make to get a seat reserved is __________

The minimum value of the function $f(x)=\frac{1}{3} x(x^2-3)$ in the interval $-100≤x≤100$ occurs at $x =$ ________.

The switch in the circuit, shown in the figure, was open for a long time and is closed at $t=0$. The current $i(t)$ (in ampere) at $t=0.5$ seconds is ____________

Consider the circuit shown in the figure. The Thevenin equivalent resistance (in Ω) across P-Q is _____________

Consider an LTI system with magnitude response $$\mid H(f) \mid=\begin{cases} 1-\frac{\mid f \mid}{20}, & \mid f \mid \leq 20 \\ 0,& \mid f \mid > 20 \end{cases}$$ and phase response $$\arg \{ H(f) \}= – 2f.$$ If the input to the system is …

The transfer function of a causal LTI system is $H(s)=1/s$. If the input to the system is $x(t)=[\sin(t)/\pi t] u(t)$, where $u(t)$ is a unit step function, the system output $y(t)$ as $t\to \infty$ is ____________

Consider the parallel combination of two LTI systems shown in the figure. The impulse responses of the systems are $$\begin{array} {} h_1(t)=2\delta (t+2)-3\delta (t+1) \\ h_2(t)=\delta (t-2). \end{array}$$ If the input $x(t)$ is a unit step signal, then the energy of $y(t)$ is ____________

A MOS capacitor is fabricated on $p$-type Si (Silicon) where the metal work function is $4.1$ eV and electron affinity of Si is $4.0$ eV. $E_C-E_F=0.9$ eV, where $E_C$ and $E_F$ are the conduction band minimum and the Fermi energy levels of Si, respectively. Oxide $\epsilon _r=3.9$, $\epsilon _o=8.85\times 10^{-14}$ F/cm, oxide thickness …

For a particular intensity of incident light on a silicon $pn$ junction solar cell, the photocurrent density $(J_L)$ is $2.5 mA/cm^2$ and the open-circuit voltage ($V_{oc}$) is $0.451$ V. Consider thermal voltage ($V_T$) to be $25$ mV. If the intensity of the incident light is increased by $20$ times, assuming that the temperature remains …

Two n-channel MOSFETs, T1 and T2, are identical in all respects except that the width of T2 is double that of T1. Both the transistors are biased in the saturation region of operation, but the gate overdrive voltage ($V_{GS}-V_{TH}$) of T2 is double that of T1,where $V_{GS}$ and $V_{TH}$ are the gate-to-source voltage and threshold voltage of the …

An abrupt $pn$ junction (located at $x=0$) is uniformly doped on both $p$ and $n$ sides. The width of the depletion region is $W$ and the electric field variation in the $x$-direction is $E(x)$. Which of the following figures represents the electric field profile near the $pn$ junction?

Assuming that transistors $M_1$ and $M_2$ are identical and have a threshold voltage of $1$ V, the state of transistors $M_1$ and $M_2$ are respectively