When an air bubble of radius \(r\) rises from the bottom to the surface of a lake, its radius becomes \(\frac{{5r}}{4}\).Taking the atmospheric pressure to be equal to \(10\,m\) height of water column, the depth of the lake would approximately be ....... \(m\) (ignore the surface tension and the effect of temperature)

Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom. The gas is maintained at a temperature of \(T\). The total internal energy, \(U\) of a mole of this gas, and the value of \(\gamma\left(=\frac{ C _{ P }}{ C _{ v }}\right)\) given, respectively, by

The distance travelled by a particle is related to time \(t\) as \(x =4 t ^2\). The velocity of the particle at \(t =\) \(5 s\) is \(.........ms^{-1}\)

A radioactive nucleus \(A\) with a half life \(T\), decays into a nucleus \(B.\) At \(t = 0\), there is no nucleus \(B\). At sometime \(t\), the ratio of the number of \(B\) to that of \(A\) is \(0.3\). Then, \(t\) is given by

In the given figure, two wheels \(P\) and \(Q\) are connected by a belt \(B\). The radius of \(P\) is three times as that of \(Q\). In case of same rotational kinetic energy, the ratio of rotational inertias \(\left(\frac{{I}_{1}}{{I}_{2}}\right)\) will be \({x}: 1\). The value of \({x}\) will be \(.....\, .\)

The fundamental frequency of vibration of a string stretched between two rigid support is \(50\,Hz\). The mass of the string is \(18\,g\) and its linear mass density is \(20\,g / m\). The speed of the transverse waves so produced in the string is \(..........\,ms ^{-1}\)

The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2 m away from it, is :

The temperature at which the kinetic energy of oxygen molecules becomes double than its value at \(27^{\circ}\,C\) is \(............^{\circ}\,C\)

Match List\(-I\) with List\(-II\)

List \(-I\)	List \(-II\)
\((A)\) Moment of inertia of solid sphere of radius \((R)\) about any tangent	\((I)\)  \(\frac{5}{3} MR ^{2}\)
\((B)\) Moment of inertia of hollow sphere of radius \((R)\) about any tangent	\((II)\) \(\frac{7}{5} MR ^{2}\)
\((C)\) Moment of inertia of circular ring of radius \((R)\) about its diameter.	\((III)\) \(\frac{1}{4} MR ^{2}\)
\((D)\) Moment of inertia of circular disc of radius \((R)\) about any diameter.	\((IV)\) \(\frac{1}{2} MR ^{2}\)

Question: Choose the correct answer from the options given below

The horizontal component of earth's magnetic field at a place is \(3.5 \times 10^{-5} \mathrm{~T}\). A very long straight conductor carrying current of \(\sqrt{2} A\) in the direction from South east to North West is placed. The force per unit length experienced by the conductor is _______ \(\times 10^{-6} \mathrm{~N} / \mathrm{m}\).

A beam of electrons of energy \(E\) scatters from a target having atomic spacing of \(1\, A\). The first maximum intensity occurs at \(\theta=60^{\circ} .\) Then \(E\) (in \(eV )\) is\(......\) (Planck constant \(h =6.64 \times 10^{-34}\, Js\) \(1 \,eV =1.6 \times 10^{-19}\,J\), electron mass \(\left. m =9.1 \times 10^{-31}\, kg \right)\) 

A point particle of mass, moves along the uniformly rough track \(PQR\) as shown in the figure. The coefficient of friction, between the particle and the rough track equals \(\mu\). The particle is released, from rest, from the point \(P\) and it comes to rest at a point \(R\). The energies, lost by the ball, over the parts, \(PQ\) and \(PR\), of the track, are equal to each other, and no energy is lost when particle changes direction from \(PQ\) to \(QR\). The values of the coefficient of friction \(\mu\) and the distance \(x(=QR)\) are, respecitvely close to

The decay of a proton to neutron is :