A thin rod having a length of \(1\; m\) and area of cross-section \(3 \times 10^{-6}\,m ^2\) is suspended vertically from one end. The rod is cooled from \(210^{\circ}\,C\) to \(160^{\circ}\,C\). After cooling, a mass \(M\) is attached at the lower end of the rod such that the length of rod again becomes \(1\,m\). Young's modulus and coefficient of linear expansion of the rod are \(2 \times 10^{11} Nm ^{-2}\) and \(2 \times 10^{-5} K ^{-1}\), respectively. The value of \(M\) is \(.......kg .\left(\right.\) Take \(\left.g=10\,m s ^{-2}\right)\)

If two charges \(q _1\) and \(q _2\) are separated with distance ' \(d\) ' and placed in a medium of dielectric constant \(K\). What will be the equivalent distance between charges in air for the same electrostatic force?

Identify the operation performed by the circuit given below

Consider an electromagnetic wave propagating in vacuum . Choose the correct statement

A small spherical ball of radius \(r\), falling through a viscous medium of negligible density has terminal velocity ' \(v\) '. Another ball of the same mass but of radius \(2 r\), falling through the same viscous medium will have terminal velocity _______.

A Helmholtz coil has pair of loops, each with \(N\) turns and radius \(R\). They are placed coaxially at distance \(R\) and the same current \(I\) flows through the loops in the same direction. The magnitude of magnetic field at \(P\), midway between the centres \(A\) and \(C\), is given by (Refer to figure)

The threshold frequency of metal is \(f_0\). When the light of frequency \(2 f_0\) is incident on the metal plate, the maximum velocity of photoelectron is \(v_1\). When the frequency of incident radiation is increased to \(5 f _0\). the maximum velocity of photoelectrons emitted is \(v_2\). The ratio of \(v_1\) to \(v_2\) is:

If \(\left(\frac{1+i}{1-i}\right)^{\frac{m}{2}}=\left(\frac{1+i}{i-1}\right)^{\frac{n}{3}}=1,(m, n \in N)\) then the greatest common divisor of the least values of \(m\) and \(n\) is

In photoelectric effect, the stopping potential \(\left(\mathrm{V}_0\right) \mathrm{v} / \mathrm{s}\) frequency \((\nu)\) curve is plotted.
( h is the Planck's constant and \(\phi_0\) is work function of metal )
(A) \(\mathrm{V}_0 \mathrm{v} / \mathrm{s} \nu\) is linear.
(B) The slope of \(\mathrm{V}_0 \mathrm{v} / \mathrm{s} \nu\) curve \(=\frac{\phi_0}{\mathrm{~h}}\)
(C) h constant is related to the slope of \(\mathrm{V}_0 \mathrm{v} / \mathrm{s} \nu\) line.
(D) The value of electric charge of electron is not required to determine \(h\) using the \(V_0 \mathrm{v} / \mathrm{s} \nu\) curve.
(E) The work function can be estimated without knowing the value of \(h\).
Choose the correct answer from the options given below :

The angular width of the central maximum in a single slit diffraction pattern is \(60^o \) . The width of the slit is \(1\ \mu m\). The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at  distance \(50\ cm\) from the slits. If the observed fringe width is \(1\ cm\), what is slit separation distance?.........\(\mu m\)
(i.e. distance between the centres of each slit. )

Let the area enclosed by the \(x\)-axis, and the tangent and normal drawn to the curve \(4 x ^{3}-\) \(3 x y^{2}+6 x^{2}-5 x y-8 y^{2}+9 x+14=0\) at the point \((-2,3)\) be \(A\). Then \(8 A\) is equal to \(.......\)

The solid cylinder of length \(80\, {cm}\) and mass \({M}\) has a radius of \(20\, {cm}\). Calculate the density of the material used if the moment of inertia of the cylinder about an axis \(CD\) parallel to \({AB}\) as shown in figure is \(2.7\, {kg} {m}^{2}\)

The lines \(\overrightarrow{ r }=(\hat{ i }-\hat{ j })+\ell(2 \hat{ i }+\hat{ k })\) and \(\overrightarrow{ r }=(2 \hat{ i }-\hat{ j })+ m (\hat{ i }+\hat{ j }-\hat{ k })\)