DATTATREYA INSTITUTE OF PHYSICS
chapter 1 to 14 Std 12 : Physics
//X
imp mcq
•
A Choose correct answer from the given options. [Each carries 1 Mark] [40]
1. In figure, two positive charges q2 and q3 fixed along the y-axis, exert a net electric force in the
+ x direction on a charge q1 fixed along the x- axis. If a positive charge Q is added at (x, 0), the
force on q1.
(A) shall increase along the positive x-axis.
(B) shall decrease along the positive x-axis.
(C) shall point along the negative x-axis.
(D) shall increase but the direction changes because of the
intersection of Q with q2 and q3.
2. A point positive charge is brought near an isolated conducting sphere as shown in figures. The
electric field is best given by
(A) (b) (c) (d)
3. The Electric flux through the surface
(A) in figure (iv) is the largest.
(B) in figure (iii) is the least.
(C) in figure (ii) is same as figure (iii) but is smaller
than figure (iv).
(D) is the same for all the figures.
4. Five charges q1, q2, q3, q4, and q5 are fixed at their positions as shown in
→ →
∫
q
figure. S is a Gaussian surface. The Gauss’s law is given by E ⋅ ds = .
ε0
S
Which of the following statements is correct ?
→
(A) E on the LHS of the above equation will have a contribution from q1, q5 and
q3 while q on the RHS will have a contribution from q2 and q4 only.
→
(B) E on the LHS of the above equation will have a contribution from all charges while q on
the RHS will have a contribution from q2 and q3 only.
→
(C) E on the LHS of the above equation will have a contribution from all charges while q on the
RHS will have a contribution from q1, q3 and q5 only.
→
(D) Both E on the LHS and q on the RHS will have contributions from q2 and q4 only.
5. Figure shows electric field lines in which an electric dipole P is placed as shown. Which of the
following statements is correct ?
(A) The dipole will not experience any force.
(B) The dipole will experience a force towards right.
(C) The dipole will experience a force towards left.
(D) The dipole will experience a force upwards.
6. A point charge +q, is placed at a distance d from an isolated conducting plane. The field at a point
P on the other side of the plane is
(A) directed perpendicular to the plane and away from the plane.
(B) directed perpendicular to the plane but towards the plane.
, A point charge +q, is placed at a distance d from an isolated conducting plane. The field at a point
P on the other side of the plane is
(A) directed perpendicular to the plane and away from the plane.
(B) directed perpendicular to the plane but towards the plane.
(C) directed radially away from the point charge.
(D) directed radially towards the point charge.
→ →
7. If ∫ E ⋅ d S =
S
0 over a surface, then
(A) the electric field inside the surface and on it is zero.
(B) the electric field inside the surface is necessarily uniform.
(C) the number of flux lines entering the surface must be equal to the number of flux lines
leaving it.
(D) all charges must necessarily be outside the surface.
8. A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from
the centre is directed.
(A) perpendicular to the diameter (B) parallel to the diameter
(C) at an angle tilted towards the diameter (D) at an angle tilted away from the diameter
9. The Electric field at a point is
(A) always continuous.
(B) continuous if there is no charge at that point.
(C) discontinuous only if there is a negative charge at that point.
(D) discontinuous if there is a charge at that point.
10. A capacitor of 4 mF is connected as shown in the circuit as per figure. The internal resistance of
the battery is 0.5 W. The amount of charge on the capacitor plates will be
(A) 0 mC
(B) 4 mC
(C) 16 mC
(D) 8 mC
11. A positively charged particle is released from rest in an uniform electric field. The electric potential
energy of the charge.
(A) remains a constant because the electric field is uniform.
(B) increases because the charge moves along the electric field.
(C) decreases because the charge moves along the electric field.
(D) decreases because the charge moves opposite to the electric field.
12. Equipotential at a great distance from a collection of charges whose total sum is not zero are
approximately
(A) spheres (B) planes (C) paraboloids (D) ellipsoids
13. Consider a uniform electric field in the z direction. The potential is a constant
(A) in all space. (B) for any x for a given z.
(C) for any y for a given z. (D) on the x-y plane for a given z.
14. The work done to move a charge along an equipotential from A to B.
B B
→ → → →
∫A
(A) cannot be defined as − E · dl
∫A
(B) must be defined as − E · dl
(C) is zero (D) can have a non-zero value.
, 15. In a region of constant potential
(A) the electric field is uniform
(B) the electric field is zero
(C) there can be no charge inside the region.
(D) the electric field shall necessarily change if a charge is placed outside the region.
1
16. A metal rod of length 10 cm and a rectangular cross-section of 1 cm × cm is connected to a
2
battery across opposite faces. The resistance will be
1
(A) maximum when the battery is connected across 1 cm × cm faces.
2
(B) maximum when the battery is connected across 10 cm ´ 1 cm faces.
1
(C) maximum when the battery is connected across 10 cm × cm faces.
2
(D) same irrespective of the three faces.
17. Which of the following characteristics of electrons determines the current in a conductor ?
(A) Drift velocity alone. (B) Thermal velocity alone.
(C) Both drift velocity and thermal velocity. (D) Neither drift nor thermal velocity.
18. Kirchhoff’s junction rule is a reflection of
(A) conservation of current density vector.
(B) conservation of charge.
(C) the fact that the momentum with which a charged particle approaches a junction is unchanged
(as a vector) as the charged particle leaves the junction.
(D) the fact that there is no accumulation of charges at a junction.
→
19. Biot-Savart law indicates that the moving electrons (velocity v) produce a magnetic field B such
that
(A) B is perpendicular to v
(B) B is parallel to v
(C) it obeys inverse cube law.
(D) it is along the line joining the electron and point of observation.
20. An electron is projected with uniform velocity along the axis of a current carrying long solenoid.
Which of the following is true ?
(A) The electron will be accelerated along the axis.
(B) The electron path will be circular about the axis.
(C) The electron will experience a force at 45° to the axis and hence execute a helical path.
(D) The electron will continue to move with uniform velocity along the axis of the solenoid.
21. A circular current loop of magnetic moment M is in an arbitrary orientation in an external
→
magnetic field B . The work done to rotate the loop by 30° about an axis perpendicular to its
plane is
3 mB
(A) mB (B) mB (C) (D) zero
2 2
22. A charged particle would continue to move with a constant velocity in a region wherein,
→ → → → → → → →
=
(A) E 0, B ≠ 0 (B) E ≠ 0, B ≠ 0 (C) E ≠ 0, B =
0 =
(D) E =
0, B 0
23. The primary origin(s) of magnetism lies in
(A) atomic currents. (B) Pauli exclusion principle.
(C) polar nature of molecules. (D) intrinsic spin of electron.
24. In a permanent magnet at room temperature.
(A) magnetic moment of each molecule is zero.
(B) the individual molecules have non-zero magnetic moment which are all perfectly aligned.
chapter 1 to 14 Std 12 : Physics
//X
imp mcq
•
A Choose correct answer from the given options. [Each carries 1 Mark] [40]
1. In figure, two positive charges q2 and q3 fixed along the y-axis, exert a net electric force in the
+ x direction on a charge q1 fixed along the x- axis. If a positive charge Q is added at (x, 0), the
force on q1.
(A) shall increase along the positive x-axis.
(B) shall decrease along the positive x-axis.
(C) shall point along the negative x-axis.
(D) shall increase but the direction changes because of the
intersection of Q with q2 and q3.
2. A point positive charge is brought near an isolated conducting sphere as shown in figures. The
electric field is best given by
(A) (b) (c) (d)
3. The Electric flux through the surface
(A) in figure (iv) is the largest.
(B) in figure (iii) is the least.
(C) in figure (ii) is same as figure (iii) but is smaller
than figure (iv).
(D) is the same for all the figures.
4. Five charges q1, q2, q3, q4, and q5 are fixed at their positions as shown in
→ →
∫
q
figure. S is a Gaussian surface. The Gauss’s law is given by E ⋅ ds = .
ε0
S
Which of the following statements is correct ?
→
(A) E on the LHS of the above equation will have a contribution from q1, q5 and
q3 while q on the RHS will have a contribution from q2 and q4 only.
→
(B) E on the LHS of the above equation will have a contribution from all charges while q on
the RHS will have a contribution from q2 and q3 only.
→
(C) E on the LHS of the above equation will have a contribution from all charges while q on the
RHS will have a contribution from q1, q3 and q5 only.
→
(D) Both E on the LHS and q on the RHS will have contributions from q2 and q4 only.
5. Figure shows electric field lines in which an electric dipole P is placed as shown. Which of the
following statements is correct ?
(A) The dipole will not experience any force.
(B) The dipole will experience a force towards right.
(C) The dipole will experience a force towards left.
(D) The dipole will experience a force upwards.
6. A point charge +q, is placed at a distance d from an isolated conducting plane. The field at a point
P on the other side of the plane is
(A) directed perpendicular to the plane and away from the plane.
(B) directed perpendicular to the plane but towards the plane.
, A point charge +q, is placed at a distance d from an isolated conducting plane. The field at a point
P on the other side of the plane is
(A) directed perpendicular to the plane and away from the plane.
(B) directed perpendicular to the plane but towards the plane.
(C) directed radially away from the point charge.
(D) directed radially towards the point charge.
→ →
7. If ∫ E ⋅ d S =
S
0 over a surface, then
(A) the electric field inside the surface and on it is zero.
(B) the electric field inside the surface is necessarily uniform.
(C) the number of flux lines entering the surface must be equal to the number of flux lines
leaving it.
(D) all charges must necessarily be outside the surface.
8. A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from
the centre is directed.
(A) perpendicular to the diameter (B) parallel to the diameter
(C) at an angle tilted towards the diameter (D) at an angle tilted away from the diameter
9. The Electric field at a point is
(A) always continuous.
(B) continuous if there is no charge at that point.
(C) discontinuous only if there is a negative charge at that point.
(D) discontinuous if there is a charge at that point.
10. A capacitor of 4 mF is connected as shown in the circuit as per figure. The internal resistance of
the battery is 0.5 W. The amount of charge on the capacitor plates will be
(A) 0 mC
(B) 4 mC
(C) 16 mC
(D) 8 mC
11. A positively charged particle is released from rest in an uniform electric field. The electric potential
energy of the charge.
(A) remains a constant because the electric field is uniform.
(B) increases because the charge moves along the electric field.
(C) decreases because the charge moves along the electric field.
(D) decreases because the charge moves opposite to the electric field.
12. Equipotential at a great distance from a collection of charges whose total sum is not zero are
approximately
(A) spheres (B) planes (C) paraboloids (D) ellipsoids
13. Consider a uniform electric field in the z direction. The potential is a constant
(A) in all space. (B) for any x for a given z.
(C) for any y for a given z. (D) on the x-y plane for a given z.
14. The work done to move a charge along an equipotential from A to B.
B B
→ → → →
∫A
(A) cannot be defined as − E · dl
∫A
(B) must be defined as − E · dl
(C) is zero (D) can have a non-zero value.
, 15. In a region of constant potential
(A) the electric field is uniform
(B) the electric field is zero
(C) there can be no charge inside the region.
(D) the electric field shall necessarily change if a charge is placed outside the region.
1
16. A metal rod of length 10 cm and a rectangular cross-section of 1 cm × cm is connected to a
2
battery across opposite faces. The resistance will be
1
(A) maximum when the battery is connected across 1 cm × cm faces.
2
(B) maximum when the battery is connected across 10 cm ´ 1 cm faces.
1
(C) maximum when the battery is connected across 10 cm × cm faces.
2
(D) same irrespective of the three faces.
17. Which of the following characteristics of electrons determines the current in a conductor ?
(A) Drift velocity alone. (B) Thermal velocity alone.
(C) Both drift velocity and thermal velocity. (D) Neither drift nor thermal velocity.
18. Kirchhoff’s junction rule is a reflection of
(A) conservation of current density vector.
(B) conservation of charge.
(C) the fact that the momentum with which a charged particle approaches a junction is unchanged
(as a vector) as the charged particle leaves the junction.
(D) the fact that there is no accumulation of charges at a junction.
→
19. Biot-Savart law indicates that the moving electrons (velocity v) produce a magnetic field B such
that
(A) B is perpendicular to v
(B) B is parallel to v
(C) it obeys inverse cube law.
(D) it is along the line joining the electron and point of observation.
20. An electron is projected with uniform velocity along the axis of a current carrying long solenoid.
Which of the following is true ?
(A) The electron will be accelerated along the axis.
(B) The electron path will be circular about the axis.
(C) The electron will experience a force at 45° to the axis and hence execute a helical path.
(D) The electron will continue to move with uniform velocity along the axis of the solenoid.
21. A circular current loop of magnetic moment M is in an arbitrary orientation in an external
→
magnetic field B . The work done to rotate the loop by 30° about an axis perpendicular to its
plane is
3 mB
(A) mB (B) mB (C) (D) zero
2 2
22. A charged particle would continue to move with a constant velocity in a region wherein,
→ → → → → → → →
=
(A) E 0, B ≠ 0 (B) E ≠ 0, B ≠ 0 (C) E ≠ 0, B =
0 =
(D) E =
0, B 0
23. The primary origin(s) of magnetism lies in
(A) atomic currents. (B) Pauli exclusion principle.
(C) polar nature of molecules. (D) intrinsic spin of electron.
24. In a permanent magnet at room temperature.
(A) magnetic moment of each molecule is zero.
(B) the individual molecules have non-zero magnetic moment which are all perfectly aligned.
