List of top Questions asked in GATE XE

A GaP–GaAs semiconductor LED display has a band gap of 1.9 eV. The wavelength of emitted light in $\mu m$ is (rounded off to two decimal places) ..............

Match the detector for a scanning electron microscope (SEM) in Column I with the resulting output in Column II. SE: Secondary electrons; BSE: Backscattered electrons; EDS: Energy Dispersive Spectroscopy; EBSD: Electron Backscatter Diffraction \begin{tabular}{|c|c|} \hline Column I & Column II \\ \hline (P) SE Detector & (1) Elemental composition analysis \\ (Q) BSE Detector & (2) Kikuchi lines \\ (R) EDS Detector & (3) Topographic image \\ (S) EBSD Detector & (4) Compositional contrast image \\ \hline \end{tabular}

The triple point $(T_t, P_t)$ is shown in a schematic phase diagram (pressure (P) – temperature (T) plot) for a one–component system. $G_S, G_L$ and $G_V$ are the free energies of solid, liquid, and vapor, respectively. At a constant pressure, $P_t$, the correct free energy (G) versus temperature (T) plot is:

The figure below shows a plane PQR in a unit cell. The Miller indices of the plane PQR is ...........

The unit of measurement for magnetic dipole moment of a body is:

$B$ is the magnetic flux density and $T_c$ is the critical temperature. The Meissner effect is represented by:

For Al – 4.5 wt% Cu alloy, the correct sequence of precipitation during age hardening at room temperature is:

There is NO base-centered cubic lattice among the list of 14 Bravais lattices because of one or more of the following reasons:

For a conventional optical microscope, which of the following options regarding the resolution limit and the depth of field is/are correct?

A liquid flows under steady and incompressible flow conditions from station 1 to station 4 through pipe sections P, Q, R, and S as shown in figure. Consider, $d, V$, and $h$ represent the diameter, velocity, and head loss, respectively, in each pipe section with subscripts ‘P’, ‘Q’, ‘R’, and ‘S’. $\Delta h$ represents the head difference between the inlet (station 1) and outlet (station 4). All the pipe sections are placed on the same horizontal plane for which the figure shows the top view.
Which one of the following options is correct for the given flow loop?

Consider, $\mathbf{i}$ and $\mathbf{j}$ are unit vectors along $x$ and $y$ directions of a Cartesian $(x,y)$ coordinate system; respectively and $t$ is time. Temperature $(T)$ and fluid velocity $(\vec{V})$ are given for a flow field as: \[ T = x^2 + y t + 35 \] \[ \vec{V} = (4xy)\mathbf{i} + (xt - 2y^2)\mathbf{j} \] The total rate of change of temperature in the flow field (in integer) for time $t=2$ at a point $(2,3)$ is ............

Driven by a pressure gradient of 100 kPa/m, a fluid of dynamic viscosity 0.1 Pa·s flows between two fixed infinitely large parallel plates under steady, incompressible, and fully developed laminar conditions. The average velocity of the flow is 2 m/s. The gap between the parallel plates in mm (rounded off to 2 decimal places) is ............

An incompressible fluid is flowing between two infinitely large parallel plates separated by 5 mm distance. The bottom plate is stationary and the top plate is moving at a constant velocity of 5 mm/s in the direction parallel to the bottom plate. The flow of the fluid between the plates is steady, two-dimensional, laminar, and the variation of fluid velocity is linear between the plates. A square fluid element of 1 mm side is considered at equal distance from both the plates in the flow field such that one of its sides is parallel to the plates. The magnitude of circulation in mm$^2$/s (in integer) along the edges of the square fluid element is .................

Consider, a kite weighing 100 grams as essentially a rigid flat plate making an angle 8° with the horizontal and having a planform area of 0.045 m$^2$ when exposed to horizontal parallel wind of 60 km/h. The thread string of the kite makes an angle 45° with the horizontal. A tension of 450 grams in the thread is necessary to float the kite steadily. Take air density as 1.2 kg/m$^3$ and gravitational acceleration as 9.81 m/s$^2$. The lift coefficient $(C_L)$ associated with the air flow around steadily floating kite (rounded off to 2 decimal places) is ....................

A fixed control volume has four one-dimensional boundary sections (1, 2, 3, and 4). For a steady flow inside the control volume, the flow properties at each section are tabulated below:

The rate of change of energy of the system which occupies the control volume at this instant is $E \times 10^6$ J/s. Find the value of $E$ (rounded off to 2 decimal places).

Water flows through a pipe of diameter 20 cm at a flow rate of 0.025 m$^3$/s. A pitot-static tube is placed at the centre of the pipe and indicates the pressure difference of 5 cm of water column. Theoretical velocity measured through pitot-static tube when multiplied with velocity coefficient $C_V$ gives the actual velocity of the flow. If the mean velocity in the pipe is 90% of the actual velocity at the centre of the pipe and the gravitational acceleration is 10 m/s$^2$, find $C_V$ (rounded off to 2 decimal places).

Consider the steady, incompressible, and fully developed laminar flow of a fluid through a circular pipe. Here, $\Delta P$ is the pressure drop in the direction of the flow and $V$ is the average axial velocity of the fluid at any cross-section. The relation between $\Delta P$ and $V$ is: \[ \Delta P = K V^n \] Here, $K$ and $n$ are constants. Which one of the following options is the correct value of $n$?

A doublet is the resulting flow pattern when a sink and a source of equal strength are brought together. Which one of the following options correctly represents the nature of the product of the strength and the distance between them during approach?

Figure shows two parallel plates (upper plate at $x=b$ and lower plate at $x=-b$) of length $L$ (aligned in $z$ direction) and infinite width (in $y$ direction, normal to the plane of figure). Two immiscible, incompressible liquids are flowing steadily in the $z$ direction through the thin passage between the plates under the influence of horizontal pressure gradient $\dfrac{(P_0-P_L)}{L}$. During the flow, the passage is always half-filled with denser fluid I (viscosity $\mu'$) at the bottom and rest is occupied by lighter fluid II (viscosity $\mu''$; $\mu''<\mu'$). Considering exactly planar interface between the fluids and no instabilities in the flow, the shear stress $\tau_{xz}$ is expressed as: \[ \tau_{xz} = \frac{(P_0 - P_L)b}{L}\left(\frac{x}{b} - \frac{1}{2}\frac{\mu' - \mu''}{\mu' + \mu''}\right). \] Which one of the following options correctly identifies the location of the point having maximum velocity of the flow?

Group-I shows different two-dimensional bodies and Group-II mentions their total drag coefficient $(C_D)$ based on frontal area while facing parallel flow of fluid having Reynolds number $Re \geq 10^4$ along the direction of arrow. The bodies are placed symmetrically with respect to the flow direction.

Which one of the following options identifies the correct match between Group-I and Group-II, as per the concept of degree of streamlining?

A solid body of uniform specific gravity floats in a deep liquid pool. Take $B, G$, and $M$ as the centre of buoyancy, centre of gravity, and metacentre of the body, respectively. Which one of the following options is correct for the stable floatation of the body in the pool when the body is given a small tilt angle?

Figure shows the steady and incompressible flow of a fluid in the direction of arrow from section A to section D. Three pipe connectors are to be placed between sections at A and D having Total Energy Line (TEL) and Hydraulic Grade Line (HGL) as depicted in the figure. Consider, $g, P, Q, V, \gamma$, and $Z$ denote gravitational acceleration, pressure, volume flow rate, velocity, specific weight, and elevation of centerline of the pipe connectors from the datum, respectively.
Which one of the following options, in sequence, indicates the correct nature of connectors between sections A and B, B and C, and C and D in the direction of flow?

A sharp flat plate of length $L$ and infinite width is immersed parallel to a fluid stream having velocity $u_\infty$. At a point on the plate, far away from the leading edge and not near the trailing edge, the boundary layer thickness, the displacement thickness, and the momentum thickness are denoted as $\delta$, $\delta^*$, and $\theta$, respectively. Which one of the following options correctly represents the relation between these thicknesses?

Consider the following Statements [1] and [2].
Statement [1]: The Eulerian study focusses attention on individual particle and its motion is observed as a function of time.
Statement [2]: The Lagrangian study focusses attention on the motion of the particles passing through an identified point.
Which one of the following options identifies the correctness of the given statements?

Statement of Reynolds Transport Theorem is given below with three blanks: The rate of change of ____________ extensive property can be calculated by summing the rate of change of the amount of same property in the ____________ and the rate at which the property is ____________ the surface of the control volume. Which one of the following options correctly fills the blanks by using its comma-separated phrases in sequence?