Explore topic-wise InterviewSolutions in Current Affairs.

One mole of an ideal gas is contained under a weightless piston of a vertical cylinder at a temperature ${27}^{\circ }\text{C}$. The space over the piston opens into the atmosphere. What work has to be performed in order to increase isothermally, the gas volume under the piston to twice its initial value, by slowly raising the piston. (Neglect friction)

A particle with ${10}^{-11}$ coulomb of charge and ${10}^{-7}$ kg mass is moving with a velocity of ${10}^8$ m/s along the y-axis. A uniform static magnetic field B = 0.5 T is acting along the x-direction. The force on the particle is

A quantity x is defined as $x=\frac{a^2-b^2}{\sqrt{c+d}}$. Value of a, b, c and d are reported as a = 3 $\pm$0.001, b = 5 $\pm$0.0013, c = 6 $\pm$0.24 and d = 10 $\pm$ 0.4. Percentage error in x will be

A particle is moving along a straight line.Find the magnitude of angular momentum about origin when particle is at minimum distance from origin.

A simple pendulum of length l is pulled aside to make an angle $\theta$with the vertical. Find the magnitude of the torque of the weight w of the bob about the point of suspension. When is the torque zero ?

Find the acceleration ( in ${\text{m/s}}^2$) of $2\text{kg}$ block in the figures $\left(A\right)$ and $\left(B\right)$ shown at the instant when $1\text{kg}$ block falls from $2\text{kg}$ block (at $t=0$). (Systems are in equilibrium at $t=0$)
(Take $g=10m/s^2$)

The maximum range of a gun on horizontal terrain is 16 km. If g = 10m/$s^2$. What must be the muzzle velocity of the shell

1. 0

Two plane mirrors are placed perpendicular to each other and a point object $P$ is placed equidistant from both the mirrors. Find the equation of the geometerical shape at which the images of the object will lie.

Two equal and opposite charges of $4\times {10}^{-8}C$ when placed $2\times {10}^{-2}cm$ away, form a dipole. If this dipole is placed in an external electric field of $4\times {10}^8$ newton/coulomb, the value of maximum torque and the work done in rotating it through ${180}^o$ will be

The two thin coaxial rings, each of radius $a$ and having charges $+Q$ and $-Q$ respectively are separated by a distance of $s$. The potential difference between the centres of the two rings is :

The resultant amplitude due to superposition of two waves

$y_1=5\sin (wt-kx)$ and

$y_2=-5\cos (wt-kx-{30}^{\circ }$)

A trolley is accelerating down an incline of angle $\theta$ with acceleration $g\sin \theta .$ Which of the following is correct? $(\alpha$ is the constant angle made by the string with vertical)

Answer the following:

(a) The casing of a rocket in flight burns up due to friction. At whose expense is the heat energy required for burning obtained? The rocket or the atmosphere?

(b) Comets move around the sun in highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet’s velocity in general. Yet the work done by the gravitational force over every complete orbit of the comet is zero. Why?

(c) An artificial satellite orbiting the earth in very thin atmosphere loses its energy gradually due to dissipation against atmospheric resistance, however small. Why then does its speed increase progressively as it comes closer and closer to the earth?

(d) In Fig. 6.13(i) the man walks 2 m carrying a mass of 15 kg on his hands. In Fig. 6.13(ii), he walks the same distance pulling the rope behind him. The rope goes over a pulley, and a mass of 15 kg hangs at its other end. In which case is the work done greater?

Fig. 6.13

A beam of light consisting of two wavelength $6300A^{\circ }$ and $\lambda A^{\circ }$ is used to obtain interference fringes in a Young’s double slit experiment. If $4^{th}$ bright fringe of $6300A^{\circ }$ coincides with $5^{th}$ dark fringe of $\lambda A^{\circ }$, the value of $\lambda$ (in $A^{\circ })$ is

Two charges of magnitude -4C and 4C are placed at points (1, 2, 3) and (3, 4, 2) respectively. What is the dipole moment?

If the coefficient of friction between $A$ and $B$ is $\mu$, the maximum acceleration of the wedge $A$ for which $B$ will remain at rest with respect to the wedge is

A wire of cross-sectional area A at temperature t is held taut with a negligible tension between two rigid supports. If the wire is cooled to a temperature $(t-\Delta t)$, what tension is developed in the wire? The coefficient of linear expansion is $\alpha$ and Young's modulus of the wire is Y.

Point charge Q is placed at distance r from the centre of conducting sphere of radius R (r>R) which of the following is correct

1. The potential at centre is zero

2. The potential at centre is kq/r

3. The charge Sphere is zero

4. Both 2 and 3

A rigid cubical block A of mass M and side L is fixed rigidly on to another cubical block of the same dimensions and of modulus of rigidity $n$ such that the lower face of A completely covers the upper face of B. the lower face of B is rigidly held on a horizontal surface. A small F is applied perpendicular to one of the side faces of A.After the force is withdrawn, block A executes small oscillations, the time period of which is

The magnetic flux $\varphi$ (in weber) linked with a coil of resistance $10\Omega$ varies with time $t$ (in second) as $\varphi =8t^2-4t+1$. The current induced in the coil at $t=0.1s$ is

A ball is dropped vertically from a height $10\text{m}$ above the ground. It hits the ground and bounces up vertically to a height of $5\text{m}$. Neglecting subsequent motion and air resistance, which of the following options correctly represents the variation of its velocity $v$ with height $h$ above the ground.

Find the double derivate of y if $y=x^2$

In a metre bridge, the gaps are closed by resistances $P$ and $Q$, $P$ being less than $Q$. A balance is obtained when the jockey makes contact at a point of bridge wire $40\text{cm}$ from one end. On shunting the coil $Q$ with a resistance of $50\Omega$, the balance point is moved through $10\text{cm}$. The resistance $P$ and $Q$ are

A wooden block of mass $20g$ is dropped from the top of the cliff $50m$ high. Simultaneously a bullet of mass $20g$ is fired from the foot of the cliff upwards with a velocity $25m{s}^{-1}$. The bullet and the wooden block will meet each other at a distance from top of the cliff : ($g=10m{s}^{-2}$)

The distance between the wires of electric mains is $12\text{cm}$. These wires experience a force of $4g\mu \text{N}$ per unit length. The value of current flowing in each wire will be- [Take $g=9.8{\text{ms}}^{-2}$]

For the graph shown below, find the net change in angular velocity of the body during the entire motion.

1. -1.25

A ray of light makes an angle of ${10}^{\circ }$ with the horizontal above it and strikes a plane mirror which is inclined at an angle $\theta$ to the horizontal. The angle $\theta$ for which the reflected ray becomes vertical is

The Potential energy of a particle of mass $1\text{kg}$ free to mone along $X$-axis is given by $U\left(x\right)=(\frac{x^2}{2}-x)$ Joule. If total mechanical energy of the particle is $2\text{J}$, then the maximum speed of the particle is



(Assume only conservative forces acts on the particle)

In Young's double slit experiment, the separation between the slits is $0.1\text{mm}$, the wavelength of light used is $600\text{nm}$ and the interference pattern is observed on a screen $1\text{m}$ away from the slits. Find the separation between the successive bright fringes.