For a constant collector-emitter voltage of \(8\,V\), the collector current of a transistor reached to the value of \(6\,mA\) from \(4\,mA\), whereas base current changed from \(20\,\mu A\) to \(25\,\mu\,A\) value. If transistor is in active state, small signal current gain (current amplification factor) will be.

In photoelectric experiment energy of \(2.48 \mathrm{eV}\) irradiates a photo sensitive material. The stopping potential was measured to be \(0.5 \mathrm{~V}\). Work function of the photo sensitive material is _______.

A nucleus has mass number \(\alpha\) and radius \(R_{\alpha}\). Another nucleus has mass number \(\beta\) and radius \(R_{\beta}\). If \(\beta = 8\alpha\) then \(R_{\alpha}/R_{\beta}\) is :

In this figure the resistance of the coil of galvanometer \(G\) is \(2\,\Omega\). The emf of the cell is \(4\,V\). The ratio of potential difference across \(C_1\) and \(C_2\) is:

Assuming the experimental mass of \({}^{12}_{6}C\) as \(12\text{ u}\), the mass defect of \({}^{12}_{6}C\) atom is _______ \(\text{MeV}/c^2\).
(Mass of proton \(= 1.00727\text{ u}\), mass of neutron \(= 1.00866\text{ u}\), \(1\text{ u} = 931.5\text{ MeV}/c^2\) and \(c\) is the speed of the light in vacuum).

Three concentric spherical metallic shells \(X , Y\) and \(Z\) of radius \(a , b\) and c respectively \([ a < b < c ]\) have surface charge densities \(\sigma,-\sigma\) and \(\sigma\), respectively. The shells \(X\) and \(Z\) are at same potential. If the radii of \(X\) and \(Y\) are \(2\,cm\) and \(3\,cm\), respectively.The radius of shell \(Z\) is \(......cm\).

Given below are two statements. One is labelled as Assertion \(A\) and the other is labelled as Reason \(R\). Assertion A :Two identical balls \(A\) and \(B\) thrown with same velocity '\(u\) ' at two different angles with horizontal attained the same range \(R\). If \(A\) and \(B\) reached the maximum height \(h_{1}\) and \(h_{2}\) respectively, then \(R =4 \sqrt{ h _{1} h _{2}}\) Reason R: Product of said heights. \(h _{1} h _{2}=\left(\frac{u^{2} \sin ^{2} \theta}{2 g }\right) \cdot\left(\frac{u^{2} \cos ^{2} \theta}{2 g }\right)\) Choose the \(CORRECT\) answer 

At a given instant, say \(t = 0,\) two radioactive substances \(A\) and \(B\) have equal activates. The ratio \(\frac{{{R_B}}}{{{R_A}}}\) of their activities. The ratio \(\frac{{{R_B}}}{{{R_A}}}\) of their activates after time \(t\) itself decays with time \(t\) as \(e^{-3t}.\) If the half-life of \(A\) is \(ln2,\) the half-life of \(B\) is

Two wires \(A\) and \(B\) are made up of the same material and have the same mass. Wire A has radius of \(2.0 \mathrm{~mm}\) and wire \(B\) has radius of \(4.0 \mathrm{~mm}\). The resistance of wire B is \(2 \Omega\). The resistance of wire \(\mathrm{A}\) is _______ \(\Omega\).

A short straight object of height \(100\, cm\) lies before the central axis of a spherical mirror whose focal length has absolute value \(| f |=40\, cm .\) The image of object produced by the mirror is of height \(25\, cm\) and has the same orientation of the object. One may conclude from the information

One mole of an ideal diatomic gas expands from volume V to 2 V isothermally at a temperature \(27^{\circ} C\) and does W joule of work. If the gas undergoes same magnitude of expansion adiabatically from \(27^{\circ} C\) doing the same amount of work W , then its final temperature will be (close to) ___________ \({ }^{\circ} C\).

To maintain a speed of \(80\,km / h\) by a bus of mass \(500\,kg\) on a plane rough road for \(4\,km\) distance, the work done by the engine of the bus will be \(........\,kJ\). [The coefficient of friction between tyre of bus and road is \(0.04]\).