Define 1 esu of charge

AB and CD are two perpendicular diameters of a circle of circumference 20pi cm. There are +10 esu, +10 esu, +10 esu and -10 esu of charges at A, B, C and D respectively. What is the Intensity of electric field at the centre O of the circle? What is the direction of the field?

What will be the surface density of charge of a sphere of radius 4 cm, if it is given 182 esu of charge?

The mass of a metal sphere charged with +20 esu is 2g. Another smaller sphere with -128 esu of charge is suspended with a thread. The former sphere, just below this smaller one, is at rest. What is the distance between the centres of the two spheres? g="980 cm . s"^(-2)

Define 1 esu of potential.

Number of esu of charge in 1C is

What is the practical unit of charge? What is its relation with 1 esu of charge?

Define 1 coulomb of charge .

The radii of two insulated metal spheres are 5cm and 10cm. 10 e.s.u. and 15 e.s.u. of charges are respectively given to them. Find the amount of energy lost when the spheres are joined together.

Two charges, each of +10^(3) esu, are placed at two points A and B separated by a distance of 200 cm. From the middle point of AB, along its perpendicular bisector, a particle having -10^(3) esu of charge is thrown upwards with energy 10^(4) erg. Determine the maximum height attained by the particle. The effect of gravitation can be neglected.

State Coulomb's law regarding the force of interaction between two point charge. Define the unit of charge from this law.