Explore topic-wise InterviewSolutions in Current Affairs.

A train travels from city A to city B with a constant speed of 10 $m{s}^{-1}$ and return back to city A with a constant speed of 20 $m{s}^{-1}$. Find its average speed during its entire journey.

STATEMENT-1 : Two coherent point sources of light having nonzero phase difference are seperated by small distance. Then on the perpendicular bisector of line segment joining both the point sources, constructive interference cannot be obtained.
STATEMENT-2 : For two waves from coherent point sources to interfere constructively at a point, the magnitude of their phase difference at that point must be $2m\pi$ ( where m is a nonnegative integer).

The ceiling of a tunnel is 5m high. What is the maximum horizontal distance that a ball thrown with a speed of can go without hitting the ceiling of the tunnel?
$(g=10m{s}^{-2})$

A red LED emits light at $0.1$ watt uniformly around it. The amplitude of the electric field of the light at a distance of $1m$ from the diode is (in V /m)

$LetY=A^n$

A charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of the three charges will be in equilibrium, if $q$ is equal to

Why do induction always take place only in finite sized bodies and not in point objects..??

A vessel has $6\text{g}$ of hydrogen at pressure $P$ and temperature $500\text{K}$. A small hole is made in it so that hydrogen leaks out. How much hydrogen leaks out if the final pressure is $P/2$ and temperature falls to $300\text{K}$?

Two transparent mediums of refractive indices ${\mu }_1$ and ${\mu }_3$ have a solid lens shaped transparent material of refractive index ${\mu }_2$ between them as shown in figures. A ray traversing these mediums is also shown in the figures.

Column I, Column II and Column III represent different relationship among refractive index $\left(\mu \right)$, wavelength of light (l) and velocity of light (v) in 3 different media.

$\begin{array}{cccccc}& ColumnI& & ColumnII& & ColumnIII\\ \left(I\right)& {\mu }_1>{\mu }_2& \left(i\right)& {\lambda }_2>{\lambda }_3& \left(P\right)& v_2>v_1\\ \left(II\right)& {\mu }_3>{\mu }_2& \left(ii\right)& {\lambda }_1={\lambda }_3& \left(Q\right)& v_2=v_3\\ \left(III\right)& {\mu }_1>{\mu }_3& \left(iii\right)& {\lambda }_1<{\lambda }_2& \left(R\right)& v_3<v_2\\ \left(IV\right)& {\mu }_2>{\mu }_3& \left(iv\right)& {\lambda }_2<{\lambda }_3& \left(S\right)& v_1=v_3\end{array}$

Which of the combination is correct for figure 3?

An electric dipole with dipole moment $4\times {10}^{–9}$ C m is aligned at ${30}^{\circ }$ with the direction of a uniform electric field of magnitude $5\times {10}^{4}N{C}^{–1}$. Calculate the magnitude of the torque acting on the dipole.

An open pipe is suddenly closed at one end. As a result the frequency of third harmonic of the closed

Pipe is found to be higher by 100 Hz than the fundamental frequency of the openpipe.The

Fundamental frequency of open pipe is

Find the derivative of $y=(x^2+1)(x^3+3)$.

During an experiment, an ideal gas is found to obey an additional law $p{V}^2$ = constant. The gas is initially at a temperature T and volume V. Find the temperature when it expands to a volume 2V.

When radiation of wavelength $\lambda$ is incident on a metallic surface the stopping potential is 4.8 volts. If the same surface is irradiated with radiation of double the wavelength, then the stopping potential becomes 1.6 volts. Then the threshold wavelength for the surface is

An athelete takes 2 O s to reach his maximum speed of 18 O km/h. What is the magnitude of his average accelebr ation ?

A small ball is projected horizontally between two large blocks. The ball is given a velocity $V$ m/s and each of the large blocks move uniformly with a velocity of $2V$ m/s. The ball collides elastically with the blocks. If the velocity of the blocks do not change due to the collision, then find out the velocity of the ball after the $2^{nd}$ collision.

If the temperature of a uniform rod is slightly increased by $\Delta t$, its moment of inertia I about a perpendicular bisector increases by -

A body of mass $m_1$ having a velocity $u_1$, makes a collision with a body of mass $m_2$ travelling with a velocity $u_2$ in same direction. After the collision, the velocity of the mass $m_1$ becomes lesser than $2u_2$. If the collision is perfectly elastic and $m_2<<m_1$, then which of the flowing statements is correct?

Which of the following is used in optical fibres?

A spherical ball of radius $1\text{cm}$ coated with a metal having emissivity $e=0.3$ is maintained at $1000\text{K}$ temperature and suspended in a vaccum chamber whose walls are maintained at $300\text{K}$. Find the rate at which electrical energy is to be supplied to the ball to keep its temperature constant. $[\sigma =5.67\times {10}^{-8}{\text{Wm}}^2{\text{K}}^{-4}]$

A body of mass $2\text{kg}$ has kinetic energy of $400\text{J}$. A constant force of $10\text{N}$ is applied in the opposite direction of velocity. Find the magnitude of the momentum of the body $2\text{s}$ after application of the force.

A square of side $2.5\text{cm}$ is cut out from a circular disc of radius $10\text{cm}$ as shown in the figure. Take the origin at the centre of the circular disc. What will be the coordinates of the centre of mass of this new shape with respect to the origin? Consider the material used to be of uniform density.

A projectile is fired with an initial speed of $5\text{m/s}$ at an angle of ${45}^{\circ }$with the horizontal, up an inclined plane having angle of inclination ${30}^{\circ }$ from horizontal. What is the range of this projectile?
(Take $g=10m/s^2$)

A current carrying wire heats a metal rod. The wire provides a constant power $\left(P\right)$ to the rod. The metal rod is enclosed in an insulated container. It is observed that the temperature ($T$) in the metal rod changes with time ($t$) as $T\left(t\right)=T_0(1+\beta t^{\frac{1}{4}})$, where $\beta$ is a constant with appropriate dimension while $T_0$ is a constant with dimension of temperature. The heat capacity of the metal is

The velocity of a particle moving in a curvilinear path varies with time as $\overrightarrow{v}=2t^2\hat{i}+t^3\hat{j}m/s$ where $t$ is in seconds. At the end of $t=1s$, the value of tangential acceleration is

A wall is moving with constant velocity $u$ towards a fixed source of sound of frequency $f$. The velocity of sound is $v$. Then the wavelength of the sound reflected by the wall is

Two identical springs of spring constant $k$ each are connecetd in series and parallel as shown in figure. A mass $M$ is suspended from them. The ratio of their frequencies of vertical oscillation will be

A meter stick is pivoted about its centre. A piece of wax of mass $20\text{g}$ travelling horizontally and perpendicular to it at $10\text{m/s}$ strikes and adheres to one end of the stick so that the stick starts to rotate in a horizontal circle. Given the moment of inertia of the stick and wax about the pivot is $0.02{\text{kg-m}}^2$, the initial angular velocity of the stick is:

Find the value of $m$ such that the vector $4\hat{i}-2\hat{j}-2\hat{k}$ is orthogonal to the vector $-\hat{i}+2\hat{j}-m\hat{k}$

A solid sphere of radius ${}^{\prime }{r}^{\prime }$ and mass ${}^{\prime }{m}^{\prime }$ is rotating about an axis passing through its COM with an angular speed ${}^{\prime }{\omega }^{\prime }$ and has rotational kinetic energy $k_1$. If the radius of the sphere is halved and angular speed is doubled, then its rotational kinetic energy becomes $k_2$. Which of the following options is correct ?

In a system of units of force $F$, acceleration $A$ and time $T$ are taken as fundamental units, then the dimensional formula of energy is

Radius of current carrying coil is ${}^{\prime }{R}^{\prime }$. Then ratio of magnetic fields at the centre of the coil to the axial point, which is $R\sqrt{3}$ distance away from the centre of the coil is

Pressure equation of a sound wave is $P=0.02\sin (3000t-9x)$ where all quantities are in $\text{SI}$ unit. The frequency and speed of sound wave is

A body rotates about a fixed axis with an angular acceleration of one radian/second/second. Through what angle does it rotate during the time in which its angular velocity increases from 5 rad/s to 15 rad/s.

In a hydrogen discharge tube, it is observed that through a given cross-section $3.13\times {10}^{15}$ electrons are moving per second from right to left and $3.12\times {10}^{15}$ protons are moving from left to right per second. The electric current in the discharge tube and its direction will be

An interference is observed due to two coherent sources 'A' and 'B' having phase constant zero separated by a distance $4\lambda$ along the y-axis where $\lambda$ is the wavelength of the source. A detector D is moved on the positive x-axis. The number of points on the x-axis excluding the points x=0 and x=$\infty$ at which maximum will be observed is

A hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is 4.2 MHz. The speed of sound in a tissue is 1.7 $km-s^{-1}$. The wavelength of sound in the tissue is close to

[CBSE PMT 1995]

In a cylindrical water tank, there are two small holes Q and P on the wall at a depth of h₁ and at a height of h₂ respectively, as shown in the figure. Water coming out from both the holes strike the ground at the same point. The ratio of h₁ and h₂ is

A body is in motion along the positive $x$ - axis, according to the relation $x=a{\sin }^2\omega t$. Then, the variation of its kinetic energy $K$ with time $t$ may be represented by

The displacement of a body is given to be proportional to the cube of time elapsed. The magnitude of the acceleration of the body is

Which of the following does not depend upon the magnetic effect of some sort

The frequency of a photon, having energy 100 eV is $(h={6.610}^{-34}J-sec)$

If a point charge is taken from lower potential to higher potential then PE increased or decreased?