Download physics Work Sheet 1

repulsion between them is 0.025 N. calculate
the final charge on each sphere.
Class XII Physics
Work Sheet CH-1
Q10. Two point charges having equal charges
separated by 1m distance experiences a force
of 8 N. What will be the force experience by
the, if they are held in water at the same
distance. (Given Kwater=80).
Q11. How will you determine the direction of the
electric field at a point in electric field?
Q1. When a glass rod is rubbed with a silk cloth,
charges appear on both. Explain how this phenomena
is consistent with the law of conservation of charges.
Q2.
A polythene piece rubbed with wool is found
to have negative charge of 3 x 10-7 C.
i. estimate the number of electons transferred
(from which to which).
Ii. Is there a transfer of mass from wool to
polythene?
Q3.
Two charges q1 and q2 separated by small
distance, satisfy the equation q1+q2 = 0. What
this tell us about the charges.
Q4.
Two identical metallic sphere A and having
charges +4Q and -10Q are kept at certain
distance apart. A third identical uncharged
sphere C is first place in contact and then
separated. Find the final charges on sphere A
and B.
Q5.
i. Calculate the charge carried by 12.5x1018
electons.
Ii. What is the basic difference between force
between two masses and the force between
the charges?
Q6.
Does coulomb’s force on two charges are in
accordance with newton’s third law of
motion?
Q7.
In coulomb’s law F=KE.q1q2/r2 states the
factors on which the proportionality constant
Ke depends.
Q8.
Q9.
Is the force acting between two electrical
point charges q1 and q2 kept at some distance
apart in air, attractive or repulsive when
(i)q1.q2>0 ii.q1 q2 <0.
Two identical metal spheres, having unequal
opposite charge are placed at a distance of
0.90 m apart in air. After bringing them in
contact with each other, they are again placed
at the same distance apart. Now the force of
Q12. Why you take the test charge q0 very small i.e.q0
0.
Q13. Two point electric charges of unknown
magnitude and the sign are placed at a
distance d apart. The electric intensity is zero
at a point, not between the charge but on the
line joining the. Write the essential condition
for this.
Q14. The force on an electron kept in an electric field
in a particular direction is F. what will be the
magnitude and the direction of the force
experienced by a proton kept at the same
position? Mass of the proton is about 1836
times the mass the electron.
Q15. Calculate the electric field strength required just
to balance a water drop of mass 10-7 kg and
having a charge of 1.6x10-19 C. (g=10 m/s2)
Q16. A particle of mass m and charge q is release in
uniform electric field of intensity E. calculate
the kinetic energy it attain moving a distance
x.
Q17. Why electric field lines:
i. can never intersect each other.
ii. Cannot form closed loop.
Iii. Cannot have break in between.
Q18. In the figure, electric field line due to point
charges q1 and q2?
i.
what are the sign of charges q1 and q2
ii. What is the
ratio of q1 and q2?
Q30. Derive an expression for electric field intensity at
a point on the axial line of an electric dipole.
Q31. Derive an expression for intensity of the electric
field at a point on the equatorial line of dipole.
Q32. A spherical conductor is placed in uniform
electric field. Which path is followed by the lines of
force?
Q19. Sketch the electric field line, when a positively
charge is kept near a conducting plate.
Q20. Define electric flux. Give its SI unit.
Q21. A spherical balloon carries a charge which is
uniformly distributed over its surface. As the balloon
is blown up and increases in size, how does the
electric flux coming out the surface of the balloon
change?
Q22. State and prove gauss’s theorem in
electrostatics.
Q23. Using Gauss’s theorem, derive an expression for
electric field due to a uniformly charged wire of
infinite length.
Q24. Derive an expression for electric field due to a
uniformly charged infinite plane.
Q25. Applying gauss theorem, find the electric field at
any point due to an infinitely charged conducting
plate.
Q26. Two infinitely parallel plates having charge
density
(I) +σ, +σ (ii) +- σ. Derive an expression for
the electric field intensity (a) in the region between
two plate (b) outside. In what way does the infinite
extension of the plates simplify the derivation?
Q27 derive an expression for the electric field due to a
uniformly charged thin spherical shell.
Q28. Define an electric dipole and dipole moment.
Give its SI unit.
Q29. An electrical dipole is placed in an external field
of strength E. calculate the torque experienced by it,
when it rotated through a given angle. Hence, define
electric dipole moment.
i. identify two pairs of perpendicular vectors in the
expression.
ii. Show diagrammatically the orientation of the
dipole in the field for which the torque is (a)
maximum (b) half the maximum value (c) zero.