Problems on electrostatics and magnetism:-

  1. Two kinds of charges positive and negative.

The force existing in two charged particles is given by coulomb’s law as:-

 
 

The force acts along the line joining the two charges.

  1. The intensity of electric at a distance r is given by:-

  3. When the charge is distributed rather then being in discrete nature:


  1. The force acting on the particle moving in the magnetic field is:-


This force acts in the perpendicular direction to the velocity of the particle and to the direction of the applied magnetic field.

  1. The work done in moving the charge from infinity in space to a point is called as electric potential energy.
  2. The potential at a point is defines as the work done in moving the unit charge from infinity to a point in space.


  1. The potential difference is the difference in the potential at two points.


  1. Equipotential surfaces:-The collection of points forming a surface such that the potential at each point is equal.

 

Problems:- (Charges are located in free space unless specified)

Q1)            Find the electric force existing between two charges particles having a magnitude of 1C and -2C at a distance of 3 meters.

Q2)            Find the electric field at a distance of 1 meter due to a charge of magnitude 1 coulomb, 2 coulomb, 5 coulomb.

Q3)            Find the net force between two charged particles having a magnitude of 10coulomb and 15 coulomb.

Q4)            Find the net force for the following system:-

Each charge is having a magnitude = 10 coulomb.

Q5)           

The charge of 100 coulomb is spread over a surface as follows:

a.       Sphere having the radius of 5 meters

b.      Cylinder having radius of 5 meters and height of 1 meter

c.       Forms a spherical shape of radius 3 meters

d.      Spread over a wire having a length as 3 meters and radius of half centimeter

Calculate the appropriate charge density and write the units.

Q6)            The two charges of 10 micro-coulomb and 15 micro coulomb are located in Porcelain having a dielectric contestant of 6.5. Find the magnitude of force exerted by one charge on another at a distance of 10 meters.

Q7)            One charge of 50 microcoulomb and another of 100 microcoulomb re brought from infinity to two different points in space. The distance between the two points is 5 meter. The work done in bringing first charge is 1J and that for other is 2J. What is the potential difference between the two points.

Q8)            A charge of 8 microcoulomb is moving with the initial velocity of 100 m/s. The magnetic field is applied perpendicular to it. The magnitude of the magnetic field is 10Weber/m2. Find the amount of force being exerted on the charged particle.

Q9)            Consider the charge q=1μC, at point A at a distance of d1=2m from q and at distance d2=1m.

a.       If these two points are diametrically opposite to each other as shown in (a) what is the potential difference VA-VB.

b.      What is the electric potential difference if points A and B are located as shown in figure (B).

Q10)        Draw the equipotential surfaces for

a.       A point charge.

b.      A charge spread over cylinder

c.       A charge passing through a line.