23449.Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of 30° with each other. When suspended in a liquid of density 0.8 g cm–3, the angle remains the same. If density of the material of the sphere is 1.6 g cm–3, the dielectric constant of the liquid is
1
4
3
2
23450.Two charges, each equal to q, are kept at x = – a and x = a on the x–axis. A particle of mass m and charge q0 = q/2 is placed at the origin. If charge q0 is given a small displacement (y << a) along the y–axis, the net force acting on the particle is proportional to
y
–y
$\dfrac{1}{y}$
–$\dfrac{1}{y}$
23451.An electric dipole is placed at an angle of 30° with an electric field intensity 2 × 105 N/C. It experiences a torque equal to 4 N m. The charge on the dipole, if the dipole length is 2 cm, is
8 mC
2 mC
5 mC
7 μC
23452.Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2, Q3, respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells, Q1 : Q2 : Q3, is
1 : 2 : 3
1 : 3 : 5
1 : 4 : 9
1 : 8 : 18
23453.A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
The potential difference between the plates decreases K times
The energy stored in the capacitor decreases K times
The change in energy stored is $\dfrac{1}{2}CV^2\left(\dfrac{1}{K} – 1\right)$
The charge on the capacitor is not conserved