List of top Questions asked in LPUNEST

The quadratic equation \(8\sec^2x-6\sec x+1=0\) has
If 8 G.M.’s inserted between 2 and 3 then product of all 8 G.M.’s is
If \(x,y,z\) are in A.P. with common difference \(d\) and the rank of the matrix \[ \begin{pmatrix} 4 & 5 & x \\ 5 & 6 & y\\ 6 & k & z \end{pmatrix} \] is \(2\), then the values of \(k,d\) are:
The diagram of a logic circuit is given below. The output \(F\) of the circuit is represented by
A block A of mass 100 kg rests on another block B of mass 200 kg and is tied to a wall as shown in figure. The coefficient of friction between A and B is 0.2 and that between B and ground is 0.3. The minimum force required to move block B is
A fully charged capacitor \(C\) with initial charge \(q_0\) is connected to a coil of self-inductance \(L\) at \(t = 0\). The time at which the energy is stored equally in the form of electric field in the capacitor and the magnetic field in the inductor is:
A signal of frequency 20 kHz and peak voltage 5 V is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 V. Choose the correct statement
A survey of 500 television viewers produced the following information: 285 watch football, 195 watch hockey, 115 watch basketball, 45 watch football and basketball, 70 watch football and hockey, 50 watch hockey and basketball, and 50 do not watch any of the three games. The number of viewers who watch \emph{exactly one of the three games is:}
The minimum number of elements that must be added to the relation \(R=\{(1,2),(2,3)\}\) on the set \(\{1,2,3\}\) so that it becomes an equivalence relation is
In a hypothetical Bohr’s hydrogen atom the mass of the electron is doubled. The energy \(E_0\) and radius \(r_0\) of the first orbit will be (\(a_0\) is the Bohr radius for the first orbit):
A radioactive isotope is being produced at a constant rate \(X\). Half-life of the radioactive substance is \(Y\). After some time the number of radioactive nuclei becomes constant. The value of this constant is:
Two identical particles move at right angles to each other, possessing de-Broglie wavelengths \( \lambda_1 \) and \( \lambda_2 \). The de-Broglie wavelength of each of the particles in their centre of mass frame will be
An object is placed at distance of 20 cm from a plano-convex lens of focal length 15 cm (\(\mu=1.5\)). The curved surface is silvered. The image will form at
In Young’s double slit experiment, the two slits act as coherent sources of equal amplitude \(A\) and wavelength \(\lambda\). In another experiment with the same set up the two slits are sources of equal amplitude \(A\) and wavelength \(\lambda\) but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is:
The voltage time graph of a triangular wave having peak value Vo is as shown in figure.The rms value of V in time interval from t = \(0\) to \(T/4\) is
A potential difference of \(2\,\text{V}\) is applied between the opposite faces of a Ge crystal plate of area \(1\,\text{cm}^2\) and thickness \(0.5\,\text{mm}\). If the concentration of electrons in Ge is \(2 \times 10^{19}\,\text{m}^{-3}\) and mobilities of electrons and holes are \(0.36\,\text{m}^2\text{V}^{-1}\text{s}^{-1}\) and \(0.14\,\text{m}^2\text{V}^{-1}\text{s}^{-1}\) respectively, then the current flowing through the plate will be:
Modern vacuum pumps can evacuate a vessel down to a pressure of \(4.0 \times 10^{-15}\,\text{atm}\). At room temperature (300 K), taking \(R = 8.3\,\text{J K}^{-1}\text{mol}^{-1}\) and \(N_{\text{Avogadro}} = 6 \times 10^{23}\,\text{mol}^{-1}\), the mean distance between molecules of gas in an evacuated vessel will be of the order of:
Three concentric conducting shells carry charges +4Q on inner, –2Q on middle and +6Q on outer. The charge on inner surface of the outer shell is
Find equivalent capacitance between points A and B. Assume each conducting plate has same dimensions and neglect the thickness of plate. It is given that \[ \frac{6A\varepsilon_0}{d}=7\,\mu F, \] where A is the area of plates.
When an electric heater is switched on, the current \(i\) is plotted against time \(t\). Taking into account the variation of resistance with temperature, which of the following best represents the resulting curve?
A wire of mass \(100\,\text{g}\) is carrying a current of \(2\,\text{A}\) towards increasing \(x\) in the form \(y = x^2 \;(-2\,\text{m} \le x \le +2\,\text{m})\). This wire is placed in a magnetic field \(\vec{B} = -0.02\,\hat{k}\,\text{tesla}\). The acceleration of the wire (in \( \text{m s}^{-2} \)) is:
The real angle of dip at a place, if a magnet is suspended at an angle of \(30^\circ\) to the magnetic meridian and the dip needle makes an angle of \(45^\circ\) with the horizontal, is:
If gravitational acceleration at surface is \(g\), increase in P.E. lifting mass \(m\) to height equal to half radius \(R/2\) from surface will be
In the arrangement, spring constant \(k=2\) N/m, masses \(M=3\) kg and \(m=1\) kg, friction coefficient 0.1. Amplitude is 10 cm. The time period of SHM will be
A wire of variable mass per unit length is \( \mu = \mu_0 x \), hanging from the ceiling as shown in the figure. A small transverse disturbance is produced at its lower end. Find the time after which the disturbance will reach to the other end.