A charged particle of mass m and charge q describes circular motion of radius r in a unifrom magnetic fiels of strenght b the frequency of revolution is

The magnetic field at the centre of an equilateral triangular loop of side 2L and carrying a current i is

A condenser of capacity $C_1$ is charged to a potential $V_0.$ The electrostatic energy stored in it is $U_0.$ It is connected to another uncharged condenser of capacity $C_2$ in parallel. The energy dissipated in the process is

Two short dipoles $p\hat{k}$ and $\frac{P}{2}\hat{k}$ are located at $\left(0,0,0\right)$ & $\left(1m,0,2m\right)$ respectivley. The resultant electric field due to the two dipoles at the point $\left(1m,0,0\right)$ is

Two conductors have the same resistance at $0^{\circ }C$ but their temperature coefficient of resistanc are ${\alpha }_1\text{and}{\alpha }_2.$ The respective temperature coefficients of their series and parallel combinations are nearly

A condenser having a capacity of $6\mu F$ is charged to $100V$ and is then joined to an uncharged condenser of $14\mu F$ and then removed. The ratio of the charges on $6\mu F$ and $14\mu F$ and the potential of $6\mu F$ will be

A wire of length l is bent in the form a circular coil of some turns. A current I flows through the coil. The coil is placed in a uniform magnetic field B. The maximum torqur on the coil can be

A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field with its plane perpendicular to the field. An emf is induced in the loop if
(i) it is traslated
(ii) it is rotated about its axis
(iii) it is rotated about a diameter
it is deformed

A close organ pipe of diameter 10 cm has length 42 cm. the air column in pipe vibrates in its second overtone with the maximum amplitude $\Delta P_o.$ The pressure amplitude at middle of pipe is

A conducting rod $PQ$ of mass $m$ and length $l$ is placed on two long parallel (smooth and conducting) rails connected to a capacitor as shown. The rod $PQ$ is connected to a non conducting spring of spring constant $k$, which is initially in relaxed state. The entire arrangement is placed in a magnetic feild perpendicular to the plane of figure.
Neglect the resistance of the rails and rod.
Now, the rod is imparted a velocity $v_0$ towards right, then acceleration of the rod as a function of its displacement $x$ given by