Explore topic-wise InterviewSolutions in Current Affairs.

White light is used to illuminate the two slits in a Young's double slits experiment. The separation between the slits is $d$ and the screen is at a distance $D(>>d)$ from the slits. At a point on the screen, directly in front of one of the slits, certain wavelengths are missing. One of these missing wavelength is:

The mass defect in a particular nuclear reaction is $0.3\text{g}$. The amount of energy liberated in kilowatt-hour $\left(\text{kWh}\right)$ is

$(\text{Velocity of light,}c=3\times {10}^8{\text{ms}}^{-1})$

The phase difference between two SHM

$y_1=10sin(10\pi t+\frac{\pi }{3})and{y}_2=12sin(8\pi t+\frac{\pi }{4})att=0.5sis:$

The angle between any two diagonals of a cube is

A $60kg$ body is pushed with just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficients of static friction and sliding friction are $0.5$ and $0.4$ respectively. The acceleration of the body is

(Take $g=10m/s^2$)

In a simple pendulum, the breaking strength of the string is double the weight of the bob. The bob is released from rest when the string is horizontal. The string breaks when it makes an angle $\theta$ with the vertical. Then

Two glass bulbs of equal volumes connected by a narrow tube are filled with a gas at $0^{\circ }C$ and a pressure of 76 cms of Hg. One of the bulbs is then placed in a water bath maintained at ${62}^{\circ }C$. What is the new value of the pressure inside the bulb? The volume of connecting tube is negligible

A fish looking from within water sees the outside world through a circular horizon. If the fish is $\sqrt{7}m$ below the surface of water, then the radius of the circular horizon will be

A body of mass 1kg and 10kg are dropped simultaneously from the top of a tower. The ratio of the time taken by them to reach the ground is

A thin uniform vertical rod of mass $m$ and length $l$ is hinged about the point $O$ as shown in the figure. The combined stiffness of springs is equal to $k$. Considering the springs to be light, find the angular frequency of small oscillations.

The electric field inside a region surrounding the origin is uniform and along the $x-$axis. A small circle is drawn with the center at the origin cutting the axis at points $\text{A}$, $\text{B}$, $\text{C}$ and $\text{D}$ having coordinates $\left(a,0\right)$, $\left(0,a\right)$, $\left(-a,0\right)$ and $\left(0,-a\right)$. Then potential is minimum at

A ball collides elastically with another ball of the same mass. The collision is oblique and initially second ball was at rest. After the collision, the two balls move with same speeds. What will be the angle between the velocities of the balls after the collision?

No photoelectrons are emitted from a metal if the wavelength of light exceeds $6000\stackrel{\circ }{A}$. The work function of the metal is approximately equal to

In an atom for the electron to revolve around the nucleus, the necessary centripetal force is obtained from the following force exerted by the nucleus on the electron

1. 0.75

A charge of $9\times {10}^{-8}\text{C}$ is distributed uniformly on the surface of a sphere of radius $1\text{cm}$. It is covered by a concentric, hollow conducting sphere of radius $5\text{cm}$. Find the electric flux through the hollow sphere.

(Take ${ϵ}_o=9\times {10}^{-12}{\text{C}}^2/{\text{N-m}}^2$)

How does piezoelectric material helps "lighter " work.... What is its mechanism?

A source of sound emits waves with frequency f Hz and speed V m/sec. Two

observers move away from this source in opposite directions each with a

speed 0.2 V relative to the source. The ratio of frequencies heard by the two

observers will be

For a wheel rotating at a rate of $60\text{rpm}$ about an axis passing through its centre, the torque required to stop wheel's rotation in 2 minute will be (Given : MOI of wheel about its axis is $4{\text{kg m}}^2)$

Photoelectric emission is observed from a surface for frequencies $v_1$ and $v_2$ of the incident radiation ($v_1>v_2$). If the maximum kinetic energies of the photoelectrons in the two cases are in the ratio 1 : k then the threshold frequency $v_0$ is given by

A $20\text{V}$ a.c. is applied to a circuit consisting of a resistance and a coil with a negligible resistance. If the voltage across the resistance is $12\text{V}.$ The voltage across the coil is-

Consider the following statements:

$A.$ Atoms of each element emit characteristics spectrum.

$B.$ According to Bohr's Postulate, an electron in hydrogen atom, revolves in a certain stationary orbit.

$C.$ The density of nuclear matter depends on the size of the nucleus.

$D.$ A free neutron is stable but a free proton decay is possible.

$E.$ Radioactivity is an indication of the instability of nuclei.

Choose the correct answer from the options given below

A boy tied a string to one of the ends of a box and started sliding the box on a playground. He then observed a circular track and rushed there and completed half revolution of the track with his box. The work done by friction on the box is _____.

Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of the energy needed for is taken from the water itself and the water is cooled down. If pitcher has $10\text{kg}$ of water, find the time in which the temperature of water falls by $5^{\circ }\text{C}$. The approximate rate of vaporisation is $5{\text{g min}}^{-1}$ $(C_w=1{\text{cal/g-}}^{\circ }\text{C},L_v=540\text{cal/g})$

A spherical liquid drop is placed on a horizontal plane. A small disturbance causes the volume of the drop to oscillate. The time period of oscillation $\left(T\right)$ of the liquid drop depends on radius $\left(r\right)$ of the drop, density $\left(\rho \right)$ and surface tension $\left(S\right)$ of the liquid. Which among the following will be a possible expression for $T$ (where $k$ is a dimensionless constant)? (given surface tension is force per unit length)