Explore topic-wise InterviewSolutions in Current Affairs.

In YDSE experiment slits are replaced by electron gun emitting electrons at speed ${10}^{7}m/s$. Slit seperation was $0.5mm$ and screen is at $1m$ from gun. Fringe width obtained at screen due to interference is approximately

Two point charges $q_1=+9\mu C$ and $q_2=-1\mu C$ are held $10\text{cm}$ apart. Where should at third charge $+Q$ be placed from $q_2$ on the line joining them so that charge $Q$ does not experience any net force ?

16 g of radioactive radon is kept in a container. How much radon will disintegrate in 19 days? Half life of radon is 3.8 days.

Water is flowing continuously from a tap having an internal diameter $8\times {10}^{-3}\text{m}$. The water velocity as it leaves the tap is $0.4\text{m/s}$. The diameter of the water stream at a distance $2\times {10}^{-1}\text{m}$ below the tap is close to

The upper end of a wire of radius 4 mm and length 100 cm is clamped and its other end is twisted through an angle of ${30}^o$. Then angle of shear is

An electric current flows along conductor AB as shown in figure.



$\overrightarrow{E}$ in conductor AB varies as

A point object is placed in front of a plane mirror, at distance $d$ from the centre of the mirror of width $L$ as shown in the figure. An observer is moving on a straight line on the same side of the mirror, parallel to it at a distance $2d$ from the mirror. The range of distance over which the observer can see the image of the object in the mirror is

A small equilateral triangular loop of side $l=1cm$ is kept inside a large circular loop of radius r such that both are coplanar and concentric. If current in the larger loop is as shown in the graph, then find the current induced in the smaller loop during the time instants given. Take anticlock wise current as positive.


List - 1 gives time instants and list - 2 gives induced current in the smaller loop. Take $\frac{{\mu }_0\pi }{2rR}=1$ where R is resistance of small loop.
$\begin{array}{cccc}& \text{List -1}& & \text{List -2}\\ \left(I\right)& 0sec& \left(p\right)& 25\mu A\\ \left(II\right)& \frac{1}{3}sec& \left(Q\right)& 12.5\mu A\\ \left(III\right)& \frac{3}{2}sec& \left(R\right)& 0\mu A\\ \left(IV\right)& \frac{5}{3}sec& \left(S\right)& -6.25\mu A\\ & & \left(T\right)& -12.5\mu A\\ & & \left(U\right)& -25\mu A\end{array}$

A particle is fired with velocity $u$ making angle $\theta$ with the horizontal. What is the magnitude of change in velocity when it is at the highest point?

An ideal gas expands isothermally from volume $V_1$ to $V_2$ and is then compressed to original volume $V_1$ adiabatically. Initial pressure is $P_1$ and final pressure is $P_3$. The total work done by gas during the whole process is $W$. Then identify the correct statement.

Let $I=\underset{0}{\overset{100\pi }{\int }}\sqrt{1-\cos 2x}dx$, then

In the figure shown , if a parallel beam of white light is incident on the pair of the slits then the distance of the nearest white spot on the screen from $O$ is : [Assumed $d<<D,\lambda <<d]$

The osmotic potential and pressure potential of three cells (A, B, C) located in different parts of an actively transpiring plant are as following.

$\begin{array}{ccc}\text{Cell}& \text{Osmotic potential (MPa)}& \text{Pressure potential(MPa)}\\ A.& -0.87& 0.44\\ B.& -0.92& 0.34\\ C.& -0.68& 0.27\end{array}$

Which of the cells (A, B, C) have the highest water potential?

An electron is emitted with negligible speed from the negative plate of a parallel plate capacitor charged to a potential difference V. The separation between the plates is d and a magnetic field B exists in the space as shown in figure (34-E20). Show that the electron will fail to strike the upper plate if

$d>{\left(\frac{2m_{e}V}{e{B}_0^2}\right)}^{\frac{1}{2}}.$

Two identical charged spheres suspended from a common point by two massless strings of lengths $l$, are initially at a distance $d(d<<l)$ apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity $v$. Which of the following correctly represent the variation of $v$ as a function of the distance $x$ between the spheres.

Figure shows the curve $y=x^2$.Find the area of the shaded part between $x=0$ and $x=6$

Seven homo genous bricks , each of length $L$ , are arranged as shown below. Each brick is displaced with respect to the one in contact by $\frac{L}{10}$. Find $X$ coordinate of the centre of mass relative to the origin shown

A potentiometer wire of length $100\text{cm}$ has a resistance of $10\Omega$. It is connected in series with a resistance and a cell of emf $2\text{V}$ and of negligible internal resistance. A source of emf $10\text{mV}$ is balanced against a length of $40\text{cm}$ of the potentiometer wire. What is the value of external resistance?

Consider a system of 4 charged particles each of mass m placed at the vertices and centre of an equilateral triangle of side a as shown in figure. Under mutually electrostatic interaction charges at vertices of the triangle are revolving in a circle. Find speed of charges. [$k=\frac{1}{4\pi {ϵ}_0}$ and neglect gravitational effect]

A sliding wire of length $0.25\text{m}$ and having a resistance of $0.5\Omega$ moves along conducting guiding rails $\text{AB}$ and $\text{CD}$ with a uniform speed of $4{\text{ms}}^{-1}$. A magnetic field of $0.5\text{T}$ exists normal to the plane of $\text{ABCD}$ directed into the page. The guiding rails are short-circuited with resistances of $4\Omega$ and $2\Omega$ as shown. The current through the sliding wire is

If $\overrightarrow{A}$ + $\overrightarrow{B}$ = $\overrightarrow{C}$ and $A^2$ + $B^2$ = $C^2$ , then find the angle between $\overrightarrow{A}$ and $\overrightarrow{B}$

A magnet is placed in the magnetic meridian with its north pole pointing north. The neutral point is obtained at a point $\text{P}$ towards east of the middle point of the magnet. When the magnet is reversed end to end at the same place, a magnetic needle completes $12$ oscillations per $\text{minute}$ at the point $\text{P}$. If the magnet be removed, how many oscillations will the needle perform per $\text{minute}$ ?

If the ratio of radii of two spheres of same material is $1:4$, then the ratio of their heat capacities will be:

Suppose the
circuit in Exercise 7.18 has a resistance of 15 Ω. Obtain the
average power transferred to each element of the circuit, and the
total power absorbed.

A circular rod which tapers uniformly from 30 mm diameter to 20 mm diameter and another rectangular bar of constant thickness 5 mm and uniformly tapering in width from 20 mm to 10 mm. The length and applied axial load are same for both the bars, the ratio of the elongation in the respective bar is ? (Take $E=2\times {10}^{5}N/m{m}^2$ for both material)

Figure 3.25 gives a speed-time graph of a particle in motion along a constant direction. Three equal intervals of time are shown. In which interval is the average acceleration greatest in magnitude? In which interval is the average speed greatest? Choosing the positive direction as the constant direction of motion, give the signs of v and a in the three intervals. What are the accelerations at the points A, B, C and D?

Three masses are placed on the $x$ - axis. A mass of $300\text{gm}$ is placed at the origin, $400\text{gm}$ at $x=40\text{cm}$ and $500\text{gm}$ at $x=70\text{cm}$ repectively. The distance of the centre of mass of the system from the origin will be:

A parallel plate capacitor has two layers of dielectric as shown in figure. This capacitor is connected across a battery. The graph which shows the variation of electric field $E$ on y-axis and distance $x$ on x-axis from left plate