MILLENNIUM PUBLIC SCHOOL
PT-1 EXAM, 2022-23
SUBJECT - PHYSICS
CLASS - XII
Time: 1 h 30 min.
MM:-40
(i) All questions are Compulsory.
(ii) The question paper has four sections; A, B, C & D.
(iii) There are four Question in total
(iv) use of calculators is not permitted.
(v) You may use the following Values of physical constants
e=1.6 x 10-19c, 1/4πε0=9x109N/C., me = 9.1x10-31kg.
Section-A.
1. (i) Is the force acting between two points electric charges q1 & q2 kept at some distance apart in air,
attractive or repulsive when (a) q1q2>0 (b) q1q2<0.
(1)
(ii) A uniform electric field E exists between two charged plates as shown in the figure what would be
the work done in moving a charge q along the closed rectangular path ABCDA?
(1)
A
B
D
C
(iii) Write an expression for Electric field & electric potential due to a point charge.
(1)
(iv) Write Coulomb law in vector form.
(1)
(v) Name the basic properties of electric charges.
(1)
(vi) Give the SI unit & dimension of Capacitance a capacitor.
(1)
Section-B
2. Attempt any five questions of the following.
(i) What is meant by quantisation of electric charge.
(ii) What is an electric dipole? Define electric dipole Moment & give its SI unit.
(iii) Why two electric lines of force never intersect each other.
(5x2=10)
(iv) calculate the electric field strength required to just support a water drop of mass 10-7 kg. &f having
charge 1.6x10-19c.
(v) what is an equipotential surface? Give an example.
(vi) Define capacitance of a capacitor & its unit.
Section-C
3. Attempt any three questions of the following.
(3×3=9)
(i) Define electric flux. A point charge of 2μc is at the centre of a cubic gaussian surface 9cm on edge.
What is the net electric flux through the surface?
(ii) State & Prove Gauss’s theorem in electrostatics.
(iii) Give the important properties of electric lines of force.
(iv) Define the following:
(a) Electric field.
(b) Electric potential of force.
Section-D
4. Attempt any three questions of the following.
(3×5=15)
(i) Define electric field intensity & drive an expression for it at a point on the axial line of dipole. Also
determine its direction.
(ii) Using Gauss’s theorem, derive an expression for the electric field intensity due to an infinitely long,
straight wire linear charge density.
(iii) Derive an expression for the electric potential at a point along the axial line of the dipole.
(iv) Three capacitors of capacitances C₁, C₂, C3 are Connected in series. Find their equivalent capacitance.