To increase the resonant frequency in series \(LCR\) circuit,

In an experiment to find \(emf\) of a cell using potentiometer, the length of null point for a cell of emf \(1.5\,V\) is found to be \(60\,cm\). If this cell is replaced by another cell of \(emf\; E\). the length-of null point increases by \(40\,cm\). The value of \(E\) is \(\frac{x}{10} V\). The value of \(x\) is \(............\)

Two electrons are moving in orbits of two hydrogen like atoms with speeds \(3 \times 10^5 m / s\) and \(2.5 \times 10^5 m / s\) respectively. If the radii of these orbits are nearly same then the possible order of energy states are _________ respectively.

The velocity of water in a river is \(18\, km/h\) near the surface. If the river is \(5\, m\) deep, find the shearing stress between the horizontal layers of water. The co-efficient of viscosity of water \(= 10^{-2}\,,poise\)

Two masses \(A\) and \(B ,\) each of mass \(M\) are fixed together by a massless spring. \(A\) force acts on the mass \(B\) as shown in figure. If the mass \(A\) starts moving away from mass \(B\) with acceleration \('a',\) then the acceleration of mass \(B\) wil be :-

Two moles of an ideal monoatomic gas occupies a volume \(V\) at \(27^o C\). The gas expands adiabatically to a volume \(2\ V\). Calculate \((a)\) the final temperature of the gas and \((b)\) change in its internal energy.

In the experimental setup of meter bridge shown in the figure, the null point is obtained at a distance of \(40\,cm\) from \(A\). If a \(10\,\Omega \) resistor is connected in series with \(R_1\), the null point shifts by \(10\,cm\). The resistance that should be connected in parallel with \(\left( {{R_1} + 10} \right)\,\Omega \) such that the null point shifts back to its initial position is .............. \(\Omega\)

Two particles \(A, B\) are moving on two concentric circles of radii \(R_1\) and \(R_2\) with equal angular speed \(\omega \). At \(t = 0,\) their positions and direction of motion are shown in the figure The relative velocity \(\overrightarrow {{V_A}}  - \overrightarrow {{V_B}} \) at \(t = \frac{\pi }{{2\omega }}\) is given by

A signal of \(0.1\, kW\) is transmitted in a cable. The attenuation of cable is \(-5 \,dB\) per \(km\) and cable length is \(20\, km\). The power received at receiver is \(10^{-x} \, W\). The value of \(x\) is ....... . \(\left[\right.\) Gain in \(\left. dB =10 \log _{10}\left(\frac{ P _{0}}{ P _{i}}\right)\right]\)

The length of wire becomes \(l_1\) and \(l_2\) when \(100\,N\) and \(120\,N\) tensions are applied respectively. If \(10l_2=11l_1\), the natural length of wire will be \(\frac{1}{x} l_1\). Here the value of \(x\) is ........

An a.c. source of angular frequency \(\omega\) is connected across a resistor \(R\) and a capacitor \(C\) in series. The current is observed as \(I\). Now the frequency of the source is changed to \(\omega/4\), (keeping the voltage unchanged) the current is found to be \(I/3\). The ratio of resistance to reactance at frequency \(\omega\) is

A charge \(q\)  is spread uniformly over an insulated loop of radius \(r\) . If it is rotated with an angular velocity \(\omega \) with respect to normal axis then the magnetic moment of the loop is

The function of time representing a simple harmonic motion with a period of \(\frac{\pi}{\omega}\) is :