Electric Charge...

Force $$F$$ between charges $$Q_{1}$$ and $$Q_{2}$$ separated by $$r$$ is $$25\ N$$. It can be reduced to $$5\ N$$ if the separation between them is made.

The electric field of a plane polarized electromagnetic Wave in free space at time t = 0 i given by an expression 
$$\vec{E} (x,y) = 10\hat{j} cos [(6x + 8z)]$$
The magenetic field $$\vec{B}$$ (x,z,t) is given by ; (c is the velocity of light will be:

Two spheres have equal and opposite charges and are at a distance of $$90\, cm$$ from each other. They are touched together and then are placed at their initial position; Then they show a repulsive force of $$0.025\, N$$. The final charge on them will be 

There is an electric field of $$100N/C$$ X-direction . the flux passing through a square of 10 cm sides placed on XY plane inside the electric field is _____ $$ Nm^2/C. $$

A positive charge particle is released in electric field in case $$(a)$$ it is just released and in case $$(b)$$ it has initial speed $$v_0$$ along electric field. If after sometime its kinetic energy in case $$(a)$$ and $$(b)$$ are $$k_1$$, and $$k_2$$ then 

An observer moves past an electron at rest. His instrument measures :

A loop of area $$4 m ^ { 2 }$$ is placed flat in the x -y plane. There is a constant magnetic field $$ 4 \hat { j }$$ in the region. Find the flux through the loop 

A small sphere of mass $$m$$ and having charge $$q$$ is suspended by a silk thread of length $$l$$ in a uniform horizontal electric filed. If it stands at a distance x from the vertical line from point of suspension, then magnitude of electric field is :

Two infinite linear charges are placed parallel to each other at a distance 0.3 m from each other. If the linear charges density in each is 5 $$\mu C/m$$, then the force acting on a unit length of each linear charge will be :-

A charge $$q$$ is placed in the middle of a line joining the two equal and like point charges $$Q$$. This system will remain in equilibrium for which the value of $$q$$ is: