A  point charge is held at the origin of a cartesian coordinate system. If a second point charge of  is moved from (0, 10, 0) to (5, 5, 5) and subsequently to (5, 0, 0), then the total work done is _______ mJ. (Round off to 2 decimal places).

Take  in SI units. All coordinates are in meters.        

Consider an electron, a neutron and a proton initially at rest and placed along a straight line such that the neutron is exactly at the center of the line joining the electron and proton. At t = 0, the particles are released but are constrained to move along the same straight line. Which of these will collide first?

A thin soap bubble of radius R = 1 cm, and thickness a = 3.3  ), is at a potential of 1 V with respect to a reference point at infinity. The bubble bursts and becomes a single spherical drop of soap (assuming all the soap is contained in the drop) of radius r . The volume of the soap in the thin bubble is  and that of the drop is . The potential in volts, of the resulting single spherical drop with respect to the same reference point at infinity is ___________. (Give the answer up to two decimal places.)

A dielectric slab with 500mm × 500mm cross –section is 0.4m long. The slab is subjected to a uniform electric field of. is equal to 2. The value of constant  is . The energy stored n the dielectric in joules is

A parallel plate capacitor has an electrode area of , with a spacing of 0.1 mm between the electrodes. The dielectric between the plates is air with a permittivity of . The charge on the capacitor is 100 V. The stored energy in the capacitor is

When the plate area of a parallel plate capacitor is increased by keeping the capacitor voltage constant, the force between the plates