1. Show does the force between two point charges change if the dielectric constant
of the medium in which they are kept increase?
[3]
2. A charged rod P attracts rod R where as P repels another charged rod Q. What
type of force is developed between Q and R?
[1]
3. A free proton and a free electron are placed in a uniform field. Which of the two
experience greater force and greater acceleration?
[2]
4. No two electric lines of force can intersect each other? Why? [2]
5. A particle of mass m and charge q is released form rest in a uniform electric
field of intensity E. calculate the kinetic energy it attains after moving a distance
s between the plates?
[3]
6. Two point charges +q and +9q are separated by a distance of 10 a. Find the point
on the line joining the two changes where electric field is zero?
[3]
7. Define the term dipole moment P
of an electric dipole indicating its direction.
Write its S.I unit. An electric dipole is placed in a uniform electric field E
. Deduce
the expression for the Torque acting on it.
[3]
8. (1) The electric field E
due to a point change at any point near to it is defined
as:
q c
F
E Lim
q
®
=
where q is the test charge and F
is the force acting on it.
What is the significance of
lim
q®o in this expression?
(2) Two charges each 2 x 10-7 C but opposite in sign forms a system. These
charges are located at points A (0,0, -10) cm and B(0,0, +10) cm
respectively. What is the total charge and electric dipole moment of the
system?
[5]
9. (a) Sketch electric lines of force due to (i) isolated positive change (ie q>0) and
(ii) isolated negative change ( ie q<0)
(b) Two point changes q and –q are placed at a distance 2a apart. Calculate the
electric field at a point P situated at a distance r along the perpendicular
bisector of the line joining the charges. What is the field when r >> a?
[5]
