Torque on a Current Loop Moving Coil Galvanometer MCQ for ISC Class-12 Ch-8 Physics . These MCQ / Objective Type Questions is based on latest reduced syllabus according 2021-22 session on bifurcated pattern. Main motto of MCQ Type Question is cracking the next upcoming exam of council. Visit official website CISCE for detail information about ISC Board Class-12 Physics.
Ch-8 Torque on a Current Loop Moving Coil Galvanometer MCQ for ISC Class-12
| Board | ISC |
| Class | 12th (XII) |
| Subject | Physics |
| Chapter-8 | Torque on a Current Loop : Moving Coil Galvanometer |
| Syllabus | on bifurcated syllabus (after reduction) |
| Session | 2021-22 |
| Topic | MCQ / Objective Type Question |
ISC Class-12 Physics Chapter-8 Torque on a Current Loop : Moving Coil Galvanometer MCQ
Question 1: The current sensitivity in the moving coil galvanometer can be expressed as?
(a) Φ/I= (NAB/k)
(b) Φ/I= k/NAB
(c) Φ/I= NAB
(d) None of these.
Answer: (a) Φ/I= (NAB/k)
Question 2: The coil of the moving coil galvanometer is wrapped over an aluminium frame as
(a) It is a good conductor.
(b) It is very tight.
(c) It is comparatively cheaper.
(d) To provide electro-magnetic damping.
Answer: (d) To provide electro-magnetic damping.
Question 3: The conversion of a moving coil galvanometer into a voltmeter is done by
(a) introducing a resistance of large value in series.
(b) introducing a resistance of small value in parallel.
(c) introducing a resistance of large value in parallel.
(d) introducing a resistance of small value in series.
Answer: (a) introducing a resistance of large value in series.
Question 4: A circular coil of radius 4 cm and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5 weber/m². The magnetic dipole moment of the coil is
(a) 0.15 ampere-m²
(b) 0.3 ampere-m²
(c) 0.45 ampere-m²
(d) 0.6 ampere-m²
Answer: (b) 0.3 ampere-m²
Question 4: A circular current loop of magnetic moment Mis 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
(a) MB
(b) √3MB2
(c) MB2
(d) zero
Answer: (d) zero
Question 5: A cubical region of space is filled with some uniform electric and magnetic fields. An electron enters the cube across one of its faces with velocity v and a positron enters via opposite face with velocity -v. At this instant,
(a) the electric forces on both the particles cause identical accelerations.
(b) the magnetic forces on both the particles cause equal accelerations.
(c) Only electron gains or looses energy.
(d) the motion of the centre of mass (CM) is determined by E alone.
Answer: (b) the magnetic forces on both the particles cause equal accelerations.
Question 6: The deflection θ is related to the electric current I in a galvanometer by the relation
(a) I ∝ θ
(b) I ∝ tan θ
(c) I ∝ sin θ
(d) I ∝ cos θ
Answer: (a) I ∝ θ
Question 7: A moving coil galvanometer carries a current I and the magnetic field B is radial. The coil has N number of turns and an effective area A. The torque acting on the coil of a moving coil galvanometer is given by
(a) NA2B2I
(b) NABI2
(c) NABI
(d) N2ABI
Answer: (c) NABI
Question 8: The sensitivity of a moving coil galvanometer can be increased by decreasing
(a) The number of turns in the coil
(b) The area of the coil
(c) The magnetic field
(d) The couple per unit twist of the suspension
Answer: (d) The couple per unit twist of the suspension
Question 9: What will be the value of sinθ when we use soft iron core in moving coil galvanometer.(Where θ is the angle between radial magnetic field and surface of the soft iron core).
(a) sinθ=0.
(b) sinθ=∞
(c) sinθ =1
(d) None of these.
Answer: (c) sinθ =1
Question 10: Moving coil galvanometer uses which principle ?
(a) Electromagnetic principle.
(b) Maxwell’s principle.
(c) The current-carrying coil experiences torque when placed in a magnetic field.
(d) None of these.
Answer: (c) The current-carrying coil experiences torque when placed in a magnetic field.
Question 11: Why we use soft iron core especially in moving coil galvanometer?
(a) Because it is ferromagnetic in nature which in turn strengthen the magnetic field lines.
(b) It is easily magnetized by the magnetizing field.
(c) It produces high magnetic field.
(d) Very high permeability.
Answer: (a) Because it is ferromagnetic in nature which in turn strengthen the magnetic field lines.
Question 12: In which way should the shunt be connected to galvanometer to make it voltmeter?
(a) In series.
(b) In parallel.
(c) Neither series nor parallel.
(d) None of these.
Answer: (a) In series.
Question 13: In ballistic galvanometer, the frame on which the coil is wound is non-metallic. It is
(a) To avoid the production of induced e.m.f
(b) To avoid the production of eddy currents
(c) To increase the production of eddy currents
(d) To increase the production of induced e.m.f
Answer: (b) To avoid the production of eddy currents
Question 14: The reason the coil is bound over the metallic frame in moving coil galvanometer is
(a) The metallic frame helps in oscillation
(b) The metallic frame helps in making steady deflection without any oscillation
(c) The metallic frame increases the magnetic field
(d) None of the above
Answer: (b) The metallic frame helps in making steady deflection without any oscillation
Question 15: The deflection in moving coil galvanometer is
(a) Inversely proportional to the area of the coil
(b) Directly proportional to the torsional constant
(c) inversely proportional to the current flowing
(d) Directly proportional to the number of turns of the coil
Answer: (d) Directly proportional to the number of turns of the coil
Question 16: The maximum current that can be measured by a galvanometer of resistance 40 Ω is 10 mA. It is converted into voltmeter that can read upto 50 V. The resistance to be connected in the series with the galvanometer is\
(a) 2010 Ω
(b) 4050 Ω
(c) 5040 Ω
(d) 4960 Ω
Answer: (d) 4960 Ω
Question 17: Two identical current carrying coaxial loops, carry current I in an opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C,
(a) ∮CB.dl = ± 2µ0I.
(b) the value of ∮CB.dl is independent of sense of C. c
(c) there may be a point on C where, B and dl are parallel.
(d) B vanishes everywhere on C.
Answer: (b) the value of ∮CB.dl is independent of sense of C. c
Question 18: A current carrying closed loop of an irregular shape lying in more than one plane when placed in uniform magnetic field, the force acting on it
(a) will be more in the plane where its larger position is covered.
(b) is zero.
(c) is infinite.
(d) may or may not be zero.
Answer: (b) is zero.
Question 19: A current loop placed in a non-uniform magnetic field experiences
(a) a force of repulsion.
(b) a force of attraction.
(c) a torque but not force.
(d) a force and a torque.
Answer: (d) a force and a torque.
Question 20: A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field B, such that B is perpendicular to the plane of the loop. The magnetic force acting on the loop is
(a) irB.
(b) 2πriB
(c) zero
(d) πriB
Answer: (c) zero
Question 21: A moving coil galvanometer can be converted into an ammeter by
(a) introducing a shunt resistance of large value in series.
(b) introducing a shunt resistance of small value in parallel.
(c) introducing a resistance of small value in series.
(d) introducing a resistance of large value in parallel.
Answer: (b) introducing a shunt resistance of small value in parallel.
Question 22: A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon
(a) area of loop
(b) value of current
(c) magnetic field
(d) None of these
Answer: (d) None of these
Question 23: The pole pieces of the magnet used in a pivoted coil galvanometer are
(a) Plane surfaces of a horse-shoe magnet
(b) Cylindrical surfaces of a bar magnet
(c) Plane surfaces of a bar magnet
(d) Cylindrical surfaces of a horse-shoe magnet
Answer: (d) Cylindrical surfaces of a horse-shoe magnet
Question 24: A current-carrying rectangular coil placed in a uniform magnetic field. In which orientation will the coil rotate?
(a) In any orientation
(b) The magnetic field is parallel to the plane of the coil
(c) The magnetic field is at 450 with the plane of the coil
(d) The magnetic field is perpendicular to the plane
Answer: (d) The magnetic field is perpendicular to the plane
Question 25: The nature of parallel and anti-parallel currents are
(a) parallel currents repel and antiparallel cur¬rents attract.
(b) parallel currents attract and antiparallel cur-rents repel.
(c) both currents attract. ’
(d) both currents repel.
Answer: (b) parallel currents attract and antiparallel cur-rents repel.
Question 26: If an electron is moving with velocity ν produces a magnetic field B , then
(a) the direction of field B will be same as the direction of velocity ν.
(b) the direction of field B will be opposite to the direction of velocity ν.
(c) the direction of field B will be perpendicular to the direction of velocity ν.
(d) the direction of field B does not depend upon the direction of velocity ν.
Answer: (c) the direction of field B will be perpendicular to the direction of velocity ν.
Question 27: In which way a shunt should be connected to galvanometer to make it ammeter?
(a) In series.
(b) Neither series nor parallel.
(c) In parallel.
(d) None of these.
Answer: (c) In parallel.
Question 28: Moving coil galvanometer contains which type of scale?
(a) Exponential scale.
(b) Linear scale.
(c) Vernier scale..
(d) None of these.
Answer: (b) Linear scale.
Question 29: What should be the order of current so that galvanometer gives full scale deflection?
(a) milli-ampere.
(b) kilo-ampere.
(c) mega-ampere.
(d) micro-ampere.
Answer: (d) micro-ampere.
Question 30: What is the shape of a magnet in moving coil galvanometer to make the radial magnetic field?
(a) Convex cylindrical magnet
(b) Horse-shoe magnet
(c) Concave cylindrical magnet
(d) None
Answer: (c) Concave cylindrical magnet
Question 31: Phospher- bronze wire is used in suspension because it has
(a) A large couple per unit twist
(b) A small couple per unit twist
(c) Low conductivity
(d) High Sensitivity
Answer: (b) A small couple per unit twist
Question 32: The gyro-magnetic ratio of an electron in an H-atom, according to Bohr model, is
(a) independent of which orbit it is in.
(b) neutral
(c) positive
(d) increases with the quantum number n.
Answer: (a) independent of which orbit it is in.
Question 33: Expression of voltage sensitivity in the moving coil galvanometer is
(a) Φ/V= NABI/kR2.
(b) Φ/V= NABI
(c) Φ/V= NAB/kR.
(d) None of these.
Answer: (c) Φ/V= NAB/kR.
Question 34: If the beams of electrons and protons move parallel to each other in the same direction, then they
(a) attract each other.
(b) repel each other.
(c) no relation.
(d) neither attract nor repel.
Answer: (b) repel each other.
Question 35: Consider a wire carrying a steady current, I placed in a uniform magnetic field B perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do not work. This implies that,
(a) motion of charges inside the conductor is unaffected by B, since they do not absorb energy.
(b) Some charges inside the wire move to the surface as a result of B.
(c) if the wire moves under the influence of B, no work is done by the force.
(d) If the wire moves under the influence of B, no work is done by the electric force on the ions, assumed fixed within the wire.
Answer: (b) Some charges inside the wire move to the surface as a result of B.
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