1. In hydrogen like system, the ratio of coulombian force and gravitational force an electron and a proton is in the order of

2. 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

3. Two charged conducting spheres of radii a and b are connected to each other by a conducting wire. The ratio of charges of the spheres respectively is  √

4. Force between two points charges q1 and q2 placed in vacuum at 'r' cm apart is F. Force between them when placed in a medium having dielectric constant k = 5 at 'r/5'cm apart will be

5. Two charges each magnitude 0.01 C and separated by a distance of 0.4 mm constitute an electric dipole. If the dipole is placed in an uniform electric field 'E' of 10 dyne/C making 30º angle with 'E' , the magnitude of torque acting on dipole is

6. The electric field due to a short electric dipole at a large distance (r) from center of dipole on the equatorial plane varies with distance as

7. A positive charge particle of 100 mg is thrown in opposite direction to a uniform electric field of strength 1 × 10^5 NC^-1 . If the charge on the particle is 40 μC and the initial velocity is 200 ms^-1 , how much distance it will travel before coming to the rest momentarily?

8. A point charge of 10 μC is placed at the origin. At what location on the X -axis should a point charge of 40 μC be placed so that the net electric field is zero at x = 2 cm on the X -axis ?

9. The bob of a simple pendulum  has mass 2 g and a charge of 5.0 μC . It is at rest in a uniform horizontal electric field of intensity 2000 V m^-1 . At equilibrium, the angle that the pendulum makes with the vertical is (take g = 10 ms ^-2)

10. Shown in the figure is a shell made of a conductor. It has inner radius a and outer radius b, and carries charge Q. At its centre is a dipole is p as shown. In this case

11. A square Q is placed at a distance a/2 above the centre of the square surface of edge a as shown in the figure . The electric flux through the square surface is

12. The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward towards the centre of Earth. This gives the total net surface charge carried by the earth to be [Given ε0 = 8.85 ×10^-12 C^2/N-m^2 , RE = 6.37 ×10^6m]

13. The electrostatic potential due to an electric dipole at a distance 'r' varies as

14. Electric potential at point 'P' due to point charge of 5 ×10^-9 C is 50 V. The distance of 'P' from the point charge is (Assume 1 /4πε0=9×10^+9 N m^2C^-2)

15. Considering a group of positive charges, which of the following statements is correct?

16. Two uniformly charged spherical conductors A and B of radii 5 mm 10 mm are separated by distance of 2 cm. If the sphere are connected by a conducting wire, then in equilibrium condition, the ratio of the magnitude of the electric fields at the surface of the sphere A and B will be

17. An electric field field of 1000V/m is applied o an electric dipole angle of 45°. The value of electric dipole moment is 10^-29 C m. What is the potential energy of the electric dipole ?

18. A charged particle q is shot towards another charged particle Q which is fixed , with a speed v. It approaches Q upto a closest distance r and then returns. If q were given a speed 2v, the closest distance of approach would be

19. On moving a charge of 20 coulomb by 2 cm, 2 J of work is done, then the potential difference between the points is

20. The equal point charges are fixed at x = -a and x = +a on the axis . Another point charge Q is placed at the origin. The charges in the electrical potential energy of Q , when it is potential by a small distance x along the x-axis, is approximately proportional to

21. A uniform electric field pointing in positive x-direction exists in a region. Let A be the origin, B be the point on the x-axis at x = +1 cm and C be the point on the y-axis at y = +1 cm. Then the potential at the point A,B and C satisfy

22. Two point charges +q and -q are held fixed at (-d,0) and (d,0) respectively of a x-y coordinate system . Then

23. A hollow metal sphere of radius 5 cm is charged such hat the potential on its surface is 10 volt. The potential at the centre of the sphere is

24. A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V . If the shell is now given a charge of -3 Q , the new potential difference the same two surface is

25. A charge q is placed at the centre of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to