Electric Charges and Fields

If the net electric field at point P along Y axis is zero, then the ratio of | q2q3 | is 85 x, where x = . [figure]

is the uniform surface charge density of a thin spherical shell of radius R. The electric field at any point on the surface of the spherical shell is :

1. / 0 R
2. / 0
3. / 2 0
4. / 4 0

Three infinitely long charged thin sheets are placed as shown in figure. The magnitude of electric field at the point P is x 0. The value of x is (all quantities are measured in SI units). [figure]

Two identical conducting spheres P and S with charge Q on each, repel each other with a force 16 N. A third identical uncharged conducting sphere R is successively brought in contact with the two spheres. The new force of repulsion between P and S is :

1. 1 N
2. 6 N
3. 12 N
4. 4 N

In hydrogen like system the ratio of coulombian force and gravitational force between an electron and a proton is in the order of :

1. 1019
2. 1039
3. 1029
4. 1036

The vehicles carrying inflammable fluids usually have metallic chains touching the ground:

1. To protect tyres from catching dirt from ground
2. It is a custom
3. To alert other vehicles
4. To conduct excess charge due to air friction to ground and prevent sparking

The electric field at point P due to an electric dipole is E. The electric field at point R on equatorial line will be Ex. The value of x : [figure]

An infinitely long positively charged straight thread has a linear charge density Cm-1. An electron revolves along a circular path having axis along the length of the wire. The graph that correctly represents the variation of the kinetic energy of electron as a function of radius of circular path from the wire is :

1. [figure]
2. [figure]
3. [figure]
4. [figure]

An infinite plane sheet of charge having uniform surface charge density + s C/m2 is placed on x-y plane. Another infinitely long line charge having uniform linear charge density + e C/m is placed at z=4 m plane and parallel to y-axis. If the magnitude values | s|=2| e| then at point (0,0,2), the ratio of magnitudes of electric field values due to sheet charge to that of line charge is n:1. The value of n is .

A charge q is placed at the center of one of the surfaces of a cube. The flux linked with the cube is:

1. q2 0
2. Zero
3. q4 0
4. q8 0