An infinite sheet carrying a uniform surface charge density σ lies on the xy-plane. The work done to carry a charge q from the point to the point (where a is a constant with the dimension of length and ε0 is the permittivity of free space) is
Consider two concentric spherical metal shells of radii r1 and r2 (r2 > r1). If the outer shell has a charge q and the inner one is grounded, the charge on the inner shell is
zero
- q
The line AA' is on charged infinite conducting plane which is perpendicular to the plane of the of the paper. The plane has a surface density of charge σ and B is ball of mass m with a like charge of magnitude q. B is connected by string from a point on the line AA'. The tangent of angle (θ) formed between the line AA' and the string is
A hollow sphere of external radius R and thickness (t << R) is made of a metal of density ρ. The sphere will float in water, if
B.
The density of material is ρ
The hollow sphere will float if its weight is less than the weight of the water displaced by the volume of the sphere. This implies mass of the sphere is less than that for the same volume of water. Now, mass of spherical cell
While the mass of water having same volume
where, ρg = density of water =
For the floatation of sphere,
A charge q is placed at one corner of a cube. The electric flux through any of the three faces adjacent to the charge is zero. The flux through any one of the other three faces is
q/3ε0
q/6ε0
q/12ε0
q/24ε0
Two charges + q and -q are placed at a distance a in a uniform electric field. The dipole moment of the combination is , where, θ is the angle between the direction of the field and the line joining the two charges. Which of the following statement(s) is/are correct ?
The torque exerted by the field on the dipole vanishes
The net force on the dipole vanishes
The torque is independent of the choice of coordinates
The net force is independent of a