A metallic sphere cools from \(50^{\circ} C\) to \(40^{\circ} C\) in \(300 \,s.\) If atmospheric temperature around is \(20^{\circ} C ,\) then the sphere's temperature after the next \(5\) minutes will be close to\(.....C\)

A line charge of length \(\frac{\text { ' } a \text { ' }}{2}\) is kept at the center of an edge \(B C\) of a cube \(A B C D E F G H\) having edge length ' \(a\) ' as shown in the figure. If the density of line charge is \(\lambda\) C per unit length, then the total electric flux through all the faces of the cube will be _______. (Take, \(\epsilon_0\) as the free space permittivity)

What is the position and nature of image formed by lens combination shown in figure? (\(f_1, f_2\) are focal lengths)

The susceptibility of a paramagnetic material is \(99\) . The permeability of the material in \(Wb / A - m\) is : [Permeability of free space \(\left.\mu_{0}=4 \pi \times 10^{-7} Wb / A -m\right]\)

A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of \(\theta ,\) where \(\theta \) is the angle by which it has rotated, is given as \(k\theta ^2.\) If its moment of inertia is \(I\) then the angular acceleration of the disc is

Given below are two statements : One is labelled as Assertion \(A\) and the other is labelled as Reason \(R\). Assertion \(A\) : \(n - p - n\) transistor permits more current than a \(p-n-p\) transistor Reason \(R\) : Electrons have greater mobility as a charge carrier Choose the correct answer from the options given below

Given below are two statements; one is labelled as Assertion \(A\) and the other is labelled as Reason \(R\). Assertion \(A:\) Electromagnets are made of soft iron. Reason \(R:\) Soft iron has high permeability and low retentivity. In the light of above, statements, choose the most appropriate answer from the options given below.

An elevator in a building can carry a maximum of \(10\) persons, with the average mass of each person being \(68\; kg\). The mass of the elevator itself is \(920\; kg\) and it moves with a constant speed \(3\; \mathrm{m} / \mathrm{s}\). The frictional force opposing the motion is \(6000 \;\mathrm{N}\). If the elevator is moving up with its full capacity, the 10.Power delivered by the motor to the elevator \(\left(\mathrm{g}=10 \;\mathrm{m} / \mathrm{s}^{2}\right)\) must be at least .............. \(\mathrm{W}\)

A charged particle carrying charge \(1\,\mu C\) is moving with velocity \((2 \hat{ i }+3 \hat{ j }+4 \hat{ k })\, ms ^{-1} .\) If an external magnetic field of \((5 \hat{ i }+3 \hat{ j }-6 \hat{ k }) \times 10^{-3}\, T\) exists in the region where the particle is moving then the force on the particle is \(\overline{ F } \times 10^{-9} N\). The vector \(\overrightarrow{ F }\) is :

A charge of \(4.0 \mu \mathrm{C}\) is moving with a velocity of \(4.0 \times 10^6 \mathrm{~ms}^{-1}\) along the positive \(\mathrm{y}\)-axis under a magnetic field \(\vec{B}\) of strength \((2 \hat{k})\  T\). The force acting on the charge is \(x \hat{i} N\). The value of \(x\) is _______.

The image of an object placed in air formed by a convex refracting surface is at a distance of \(10\, m\) behind the surface. The image is real and is at \(\frac{2}{3}\) of the distance of the object from the surface . The wavelength of light inside the surface is \(\frac{2}{3}\) times the wavelength in air. The radius of the curved surface is \(\frac{ x }{13}\, m\). the value of \(^{\prime} x^{\prime}\) is ....... .

\(27\) similar drops of mercury are maintained at \(10 \,V\) each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is ....... times that of a smaller drop.