Two short bar magnets have magnetic moments \[1.20\,\,A\,\,{{m}^{2}}\] and \[1.00\,\,A\,\,{{m}^{2}}\] respectively. They are placed on horizontal table parallel to each other with their north poles pointing towards the south. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the Mid - point 0 of the line joining their centres is (horizontal component of the Earth's magnetic induction is \[3.6\times {{10}^{-5}}Wb/{{m}^{2}})\]
A thin rod is bent in the shape of a small circle of radius r. If the charge per unit length of the rod is a, and if the circle is rotated about its axis at a rate of n rotations per second, the magnetic induction at a point on the axis at a large distance y from the center is
In a Young's double slit experiment the intensity of the resultant wave at a point P on the screen is l where the path difference between the waves from coherent sources \[{{S}_{1}}\] and \[{{S}_{2}}\] is \[\lambda \]. Then the intensity of the resultant wave at a point where the path difference is \[\lambda /4\] is given by
A point object is placed on the optic axis of a convex lens of focal length fat a distance of 2f to the left of it. The diameter of the lens is. an eye is placed at a distance of 3f to the right of the lens and a distance h below the optic axis. The maximum value of h to see the image is
Two wires AO and OC carry equal currents / as shown in figure. One end of both the wire extends to infinity. Angle AOC is a. The magnitude of magnetic field at a point P on the bisector of these two wires at a distance from point O is
Two concentric and coplanar circular coils have radii a and b \[(>>a)\] as shown in figure. Resistance of the inner coil is R. Current in the outer coil is increased from 0 to /, then the total charge circulating in the inner coil is
White light may be considered to be a mixture of waves with \[\lambda \] ranging between 3900 A and 7800 A. An oil film thickness 10,000 A is examined normally by the reflected light. If \[\mu \] = 1.4, then the film appears bright for
Two copper balls, each weighting 10 g are kept in air 10 cm apart. If one electron from every \[{{10}^{6}}\] atom is transferred from one ball to the other, the coulomb force between them is (atomic weight of copper is 63.5)
An ionized gas contains both positive and negative ions. If it is subjected simultaneously to an electric field along the + X direction and a magnetic field along the + Z direction, then
A)
Positive ions deflect towards + Y direction and negative ions towards - Y direction
doneclear
B)
All ions deflect towards + Y direction
doneclear
C)
All ions deflect towards - Y direction
doneclear
D)
Positive ions deflect towards - Y direction and negative ions towards + Y direction.
In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If \[{{a}_{0}}\]is the radius of the ground state orbit, m is the mass and e is the charge on the electron and \[{{\varepsilon }_{0}}\] is the vacuum permittivity, the speed of the electron is