The electrostatic force on a small sphere of charge 0.4 \(\mu\)C due to another small sphere of charge -0.8 \(\mu\)C in air is 0.2 N.
(a) What is the distance between the two spheres?
(b) What is the force on the second sphere due to the first?

Check that the ratio ke²/Gm_em_p is dimensionless. Look up a table of physical constants and determine the value of this ratio. What does the ratio signify?

A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10^-12F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?

Three capacitors each of capacitance 9 pF are connected in series.
(a) What is the total capacitance of the combination?
(b) What is the potential difference across each capacitor, if the combination is connected to a 120 volt supply?

A 12pF capacitor is connected to a 50V battery. How much electrostatic energy is stored in the capacitor?

A 600 pF capacitor is charged by a 200 V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?

(a) conductor A with a cavity as shown in figure.
(i) is given a charge Q. Show that the entire charge must appear on the outer surface of the conductor.
(ii) Another conductor B with charge q is inserted into the cavity keeping B insulated from A. Show that the total charge on the outside surface A is Q + q Figure.
(iii) A sensitive instrument is to be shifted from the strong electrostatic field in its environment. Siggest a possible way.

Two charged conducting spheres of radii a and b are connected to each other by a wire. What is the ratio of electric fields at the surface of the two spheres? Use the result obtained to explain why charge density on the sharp and pointed ends of a conductor is higher than on its flattened portions?

What is the area of the plates of a 2F parallel plate capacitor given that the separation between the plates is 0.5 cm? You will realise from your answer why ordinary capacitors are in the range of\(\mu F\) or less.However, electrolytic capacitors do have a much larger capacitance (0.1F) because of very minute separation between the conductors.

In a Van de Graff type generator, a spherical metal shell is to be a \(15\times { 10 }^{ 6 }V\) electrode.The dielectric strength of the gas surrounding the electrode is \(5\times { 10 }^{ 7 }{ Vm }^{ -1 }\) .What is the minimum radius of the spherical shell required?
(You will learn from this exercise why one cannot build an electrostatic generator using a very small shell which requires a small charge to acquire a high potential)

Three equal charges of + qC each placed at the three corners of an equilateral triangle. Find the total force experienced by a unit charge placed at the centroid of the triangle.

Two charges each of \(5\mu C,\) but opposite in sign are placed 4 cm apart. Calculate the electric field intensity at a point distant 4 cm from the mid-point on the axial line of the dipole.

Calculate Coulomb's force between two \(\alpha -particles\) separated by a distance of \(3.2\times { 20 }^{ -15 }m.\)

Find the magnitude of electric field which just balances a deuteron of mass \(3.2\times { 10 }^{ -27 }kg.\)

Can two balls having same kind of charge on them attract each other? Explain.