S.B.I.O.A. MODEL MATRIC AND HIGHER SECONDARY SCHOOL, CHENNAI – 37
CYCLE TEST – I
STD. XII PHYSICS TIME : 1 HR.
CODE – A MAX. MARKS : 50
I. ANSWER THE FOLLOWING: 10 X 3 = 30
1. State Coulomb’s law in electrostatics.
2. What is a dipole? Define dipole moment.
3. Differentiate polar and non polar molecules.
4. What is meant by quantization of charges?
5. Define potential at a point.
6. Give the uses of capacitors.
7. What is corona discharge? Where is it used?
8. What is meant by electrostatic shielding?
9. Three small identical balls have charges -3 x 10-12 C, 8 x10-12 C and 4 x 10-12 C respectively. They
are brought in contact and then separated. Calculate (i) the charge on each ball (ii) no. of electrons
in excess or deficit in each ball after contact.
10. Two charges +q and -3q are separated by a distance of 1m. At what point between the charges on
the axis is the potential zero?
II. ANSWER THE FOLLOWING: 2 X 5 = 10
11. Derive an expression for the energy stored in a capacitor.
12. Two charges 10 x 10-9 C and 20 x 10-9 C are placed at a distance of 0.3 m apart. Find the potential
and intensity at a point midway between them.
OR
A parallel plate capacitor has plates of area 200 cm2 and separation between the plates is 1 mm.
Calculate (i) the potential difference between the plates if a 1 nC charge is given to the capacitor
(ii) with the same charge the separation between the platers is increased to 2 mm, what is the new
potential difference and (iii) the electric field between the plates.
III. ANSWER THE FOLLOWING: 1 X 10 =10
13. Derive an expression for the electric field at a point on the axial line of the dipole.
OR
Explain the principle of a capacitor. Derive an expression for the capacitance of a parallel plate
capacitor.
S.B.I.O.A. MODEL MATRIC AND HIGHER SECONDARY SCHOOL, CHENNAI – 37
CYCLE TEST – I
STD. XII PHYSICS TIME : 1 HR.
CODE – B MAX. MARKS : 50
I. ANSWER THE FOLLOWING: 10 X 3 = 30
1. State Gauss’s law in electrostatics.
2. Define electric flux and give its unit .
3. What is permittivity and relative permittivity? How are they related?
4. What is meant by additive nature of charges?
5. Define potential difference.
6. Give the properties of lines of force.
7. Explain the working of a microwave oven.
8. What is meant by electrostatic induction?
9. Three capacitors 10 µF, 20 µF and 30 µF are connected in parallel with a 100 V battery. What is the
total energy stored in the combination of capacitors?
10. A sample of HCl gas is placed in an electric field of 2.5 x 104 NC-1. The dipole moment of each
molecule is 3.4 x 10-30 C m. Find the maximum torque that can act on a molecule.
II. ANSWER THE FOLLOWING: 2 X 5 = 10
11. Derive an expression for the potential energy of a dipole.
12. Two insulated charged spheres of charges 6.5 x 10-7 C each are separated by a distance of 0.5 m.
Calculate the electrostatic force between them. Also calculate the force (i) when the charges are
doubled and the distance of separation is halved. (ii) when the charges are placed in a dielectric
medium water (εr = 80)
OR
A spherical conductor of radius 0.12 m has a charge of 1.6 x 10-7 C distributed uniformly on its
surface. What is the electric field (i) inside the sphere (ii) on the sphere (iii) at a point 0.18 m
from the centre of the sphere?
III. ANSWER THE FOLLOWING: 1 X 10 =10
13. Derive an expression for the electric field at a point on the equatorial line of the dipole.
OR
What is a capacitor? Derive an expression for the capacitance of a parallel plate
capacitor when a dielectric is introduced.
S.B.I.O.A. MODEL MATRIC AND HIGHER SECONDARY SCHOOL, CHENNAI – 37
CYCLE TEST – I
STD. XII PHYSICS – OBJECTIVE TEST TIME : 1 HR.
CODE – A MAX. MARKS : 50
S.NO. / QUESTION / OPTION / ANSWER1. / If a system consists of three charges 3q, 4q and -5q, then the total charge of the system is ______
a) 2q b) -2q c) 5q d) 12q
2. / The value of permittivity of free space is ______
a) 8.854 x 1012 C2 N-1 m-2 b) 8.854 x 10-12 C2 N-1 m-2
c) 8.854 x 1012 C2 N1 m2 d) 8.854 x 10-12 C2 N1 m2
3. / If the distance between two charges is doubled, then the force between the charges will be ______
a) four times more b) four times less
c) two times more d) two times less
4. / If a proton is moved against the coulomb force of an electric field ______
a) work is done by the field
b) energy is used from some outside source
c) the strength of the field is decreased
d) the energy of the system is decreased
5. / In vacuum the force between two charges is ______
a) F = b) F =
c) F = d) F =
6. / The unit for k = is ______
a) NmC-1 b) Nm2C-1 c) Nm-2C-1 d) Nm2C
7. / The relative permittivity of a medium is also known as ______
a) permeability b) permittivity c) dielectric constant d) relative permeability
8. / Inverse square law helps us to define ______
a) force b) charge c) newton d) coulomb
9. / If a charge of q coulomb placed at a point experiences a force of F newton, then the electric field intensity is ______
a) E = b) E = c) E = d) E =
10. / The unit of relative permittivity is ______
a) NmC-1 b) Nm2C-1 c) Nm-2C-1 d) no unit
11. / The force between two charges depends on ______
a) density of the medium
b) permeability of the medium c) nature of the medium d) size of the medium
12. / The direction dipole moment is ______
a) from +q to –q b) from –q to +q
c) either a or b d) none of the above
13. / A unit positive charge gives rise to ______lines of force in free space.
a) 1/ εr b) εr c) 1/ ε0 d) ε0
14. / The relation between electric field and electric potential is ______
a) b) c) d)
15. / The potential at a point on the equatorial line of an electric dipole is ______
a) infinity b) zero c) d)
16. / The torque acting on an electric dipole in an uniform electric field is ______
a) pE cosθ b) pE sin θ c) –pE sin θ d) 0
17. / Electric potential energy is measured in terms of ______
a) force b) work done c) intensity d) electric field
18. / The unit of electric flux is ______
a) NmC-1 b) Nm2C-1 c) Nm-2C-1 d) no unit
19. / The electric field due to an infinite plane sheet of charge is ______
a) independent of the charge on the sheet
b) independent of the area of the sheet
c) independent of the medium
d) independent of the distance of the point from the sheet
20. / The distribution of charge on a conductor depends on ______
a) only on the shape of the conductor
b) nature of the conductor
c) only on the proximity of the conductors
d) on the shape and proximity of the conductors
21. / Lightning arrestors work on the principle of ______
a) induction b) action of points c) conduction
d) electromagnetic induction
22. / Van de Graff generators are used to obtain potential of the order of ______V.
a) 10-6 b) 106 c) 107 d) 10-7
23. / The capacitance of a condenser is given by ______
a) C = q/V b) C = qV c) V = C/q d) V = qC
24. / If a dielectric is introduced in a parallel plate capacitor, it tends to ______
a) increase the capacitance b) decrease the capacitance c) neither increase nor decrease d) first increases and then decreases
25. / The commonly used dielectric is ______
a) air b) oil c) water d) wood
26. / Two point chargesd +4q and +q are placed 30 cm apart. At what point on the line joining them is the electric field zero?
a) 15 cm from +q b) 7.5 cm from +q
c) 20 cm from +4q d) 5 cm from +q
27. / The electrostatic force between two charges kept at a distance d apart in a medium εr = 6 is 0.3 N. The force between them at the same separation is ______
a) 20 N b) 0.5 N c) 1.8 N d) 2 N
28. / Electric field intensity is 400 V/m at a distance of 2 m from a point charge. It will be 100 V/m at a distance of ______
a) 50 cm b) 4 cm c) 4 m d) 1.5 m
29. / A dipole is placed with its axis parallel to a uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
30. / A dipole is placed at angle θ in an uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
32. / A dipole is placed in a non-uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
32. / If a point lies at a distance x from the midpoint of a dipole, the electric potential at this point is ______
a) directly proportional to x2
b) inversely proportional to x2
c) directly proportional to 1/x2
d) none of the above
33. / Electric potential energy of two point charges is ______
a) b)
c) pE cosθ d) pE sinθ
34. / Electric potential energy of a dipole in an electric field is ______
a) b)
c) pE cosθ d) pE sinθ
35. / The work done in moving a 500µC charge between two points on an equipotential surface is ______
a) zero b) finite positive c) finite negative d) infinity
36. / The work done in moving a 500µC charge between two points whose potential difference is 5 V is ______
a) zero b) finite positive c) finite negative d) infinity
37. / Which of the following quantities is a scalar?
a) dipole moment b) electric field
c) electric potential d) electric force
38. / The number of lines of force originating from a charge of 1C is ______
a) 1.129 b) 1.129 x 1011 c) 1.129 x10-11
d) 1.6 x 1018
39. / The number of lines of force originating from a charge of 1µC is ______
a) 1.129 x 105 b) 1.129 x 1011 c) 1.129 x10-11
d) 1.6 x 1018
40. / The electric field outside the plates of two oppositely charged plane sheets of charge density σ is ______
a) σ/2 ε0 b) -σ/2 ε0 c) σ / ε0 d) zero
41. / The electric field in between the plates of two oppositely charged plane sheets of charge density σ is ______
a) σ/2 ε0 b) -σ/2 ε0 c) σ / ε0 d) zero
42. / The electric field in between the plates of two similarly charged plane sheets of charge density σ is ______
a) σ/2 ε0 b) -σ/2 ε0 c) σ / ε0 d) zero
43. / A hollow metal ball carrying an electric charge produces no electric field at points ______
a) outside the sphere b) inside the sphere c) on its surface d) at a distance more than twice the radius
44. / The capacitance of a parallel plate capacitor increases from 5µF to 12 µF when a dielectric is filled between the plates. The dielectric constant of the dielectric is ______
a) 65 b) 55 c) 12 d) 10
45. / When capacitors are connected in parallel, the ______
a) p.d. across each capacitor is the same
b) charge through each capacitor is the same
c) both a and b d) neither a nor b
46. / If the p.d between two points 3 cm apart in an electric field is 30 V, then the electric field intensity between the points will be ______
a) 20 V/m b) 40 V/m c) 10 V/m d) 10 V/cm
47. / The force experienced by an electron in an electric field of intensity 103 V/m is ______
a) 1.6 x 10-19 N b) 1.6 x 10-16 N
c) 1.6 x 1019 N d) 1.6 x 10-10 N
48. / Distribution of charges on a conductor depends on ______
a) size b) shape c) mass d) area
49. / Relation between electric field intensity and electric potential is ______
a) dV = -E dx b) dE = -V dx
c) dV = -dE d) dV = dE
50. / The value for εr for air is ______
a) 1 b) 0 c) < 1 d) >1
S.B.I.O.A. MODEL MATRIC AND HIGHER SECONDARY SCHOOL, CHENNAI – 37
CYCLE TEST – I
STD. XII PHYSICS – OBJECTIVE TEST TIME : 1 HR.
CODE – B MAX. MARKS : 50
S.NO. / QUESTION / OPTION / ANSWER1. / Two point chargesd +4q and +q are placed 30 cm apart. At what point on the line joining them is the electric field zero?
a) 15 cm from +q b) 7.5 cm from +q
c) 20 cm from +4q d) 5 cm from +q
2. / The electrostatic force between two charges kept at a distance d apart in a medium εr = 6 is 0.3 N. The force between them at the same separation is ______
a) 20 N b) 0.5 N c) 1.8 N d) 2 N
3. / Electric field intensity is 400 V/m at a distance of 2 m from a point charge. It will be 100 V/m at a distance of ______
a) 50 cm b) 4 cm c) 4 m d) 1.5 m
4. / A dipole is placed with its axis parallel to a uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
5. / A dipole is placed at angle θ in an uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
6. / A dipole is placed in a non-uniform electric field. It experiences ______
a) only a net force b) both a net force and a torque
c) only torque d) neither a net force nor torque
7. / If a point lies at a distance x from the midpoint of a dipole, the electric potential at this point is ______
a) directly proportional to x2
b) inversely proportional to x2
c) directly proportional to 1/x2
d) none of the above
8. / Electric potential energy of two point charges is ______
a) b)
c) pE cosθ d) pE sinθ
9. / Electric potential energy of a dipole in an electric field is ______
a) b)
c) pE cosθ d) pE sinθ
10. / The work done in moving a 500µC charge between two points on an equipotential surface is ______