NEET Physics Chapter Wise Mock Test – Magnetism

NEET Physics Chapter Wise Mock Test – Magnetism

Question 1:
Two identical bar magnets each of dipole moment p_m and length l are perpendicular to each other as shown in the figure. The dipole moment of the combination is

(a) 2 p_m
(b) √2 p_m
(c) p_m/√2
(d) p_m/2

Question 2:
A small magnet of dipole moment M is kept on the arm of . a deflection magnetometer set in tanA position at a distance of 0.2 m, If the deflection is 60°, the value of M is (B_H = 0.4 x 10^-4 T)
(a) 2.77 Am²
(b) zero
(c) 10.82 Am²
(d) None of the above

Question 3:
Two short magnets of magnetic moment 2 Am² and 5 Am² are placed along two lines drawn at right angle to each other on the sheet of paper as shown in the figure. What is magnetic field at the point of intersection of their axis?

(a) 0
(b) 215 x 10^-5 T
(c) 2.15 x 10^-5 T
(d) 0.215 T

Question 4:
A current carrying circular loop of radius R is placed in the xy-plane with centre at the origin. Half of the loop with x > 0 is now bent, so that it now lies in the yz-plane.
(a) The magnitude of magnetic moment now diminishes
(b) The magnetic moment does not change
(c) The magnitude of Bat (0,0,z),z>>R increases
(d) The magnitude of Bat (0,0,z), z>>R unchanged

Question 5:
How much work is done to rotate a magnet of dipole moment p_m in a magnetic field B through 180°?
(a) p_mB/2
(b) p_mB
(c) 3p_mB/2
(d) 2p_mB

Question 6:
Two bar magnets of the same mass, same length and breadth but having magnetic moments M and 2M are joined together pole to pole and suspended by a string. The time period of assembly in a magnetic field of strength B is 3s. If now the polarity of one of the magnet is reversed and the combination is again made to oscillate in the same field, then the time of oscillation is
(a) √3 s
(b) 3√3 s
(c) 3 s
(d) 6 s

Question 7:
The period of oscillation of a magnet in a vibration magnetometer is 8s. The period of oscillation of magnet whose magnetic moment is four times that of the first magnet is
(a) 1s
(b) 4s
(c) 8s
(d) 16s

Question 8:
A thin bar magnet vibrates in the horizontal plane with a period of 8 s. The magnet is cut into two halves perpendicular to magnetic axis. Then, the period of vibration of each half is approximately
(a) 4s
(b) 2s
(c) 1s
(d) 0.5s

Question 9:
What is the angle of dip at a place, where horizontal component of earth’s magnetic field is equal to the vertical component?
(a) 0°
(b) 30°
(c) 45°
(d) 90°

Question 10:
Two magnets placed one above the other oscillate with a period of 17 s. If one of them is reversed the time period becomes 8s. The ratio of their magnetic moment is nearest to
(a) 8/17
(b) 9/14
(c) 1/4
(d) 1/2

Question 11:
A vibration magnetometer consists of two identical bar magnets placed one over the other, such- that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is 26/4 s. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in second is
(a) 21/4
(b) 21/2
(c) 2
(d) 23/4

Question 12:
In a certain place,the horizontal component of magnetic field is 1/√3 times the vertical component. The angle of dip at this place is
(a) Zero
(b) π/3
(c) π/2
(d) π/ 6

Question 13:
At a certain place, the angle of dip is 60° and the horizontal component of earth’s magnetic field is 4 x 10^-4 T. The earth’s total magnetic field is
(a) 0.02 mT
(b) 0.04 mT
(c) 0.08 mT
(d) 0.16 mT

Question 14:

Question 15:
In tanA position, two short bar magnets of moments in the ratio 1:1.7321 are placed at the same distance separately. If the deflection produced for the first magnet is 30°, then the deflection produced for the second magnet will be
(a) 60°
(b) 30°
(c) 45°
(d) 42°

Question 16:
The correct value of the dip angle at a place is 45°. The dip circle is rotated through 45° out of the magnetic meridian. The apparent angle of dip will be
(a) tan-1 (√2)
(b) tan-1 (1/√2)
(c) tan’1(2)
(d) tan’1(1/2)

Question 17:
If the magnet is suspended at an angle 30° to the magnetic meridian, the dip needle makes an angle of 60° with the horizontal. What is the true dip?
(a) tan-1 (3)
(b) tan-1 (3/2)
(c) tan-1 (2/3)
(d) tan-1 (1/3)

Question 18:
Two small magnets A and B of dipole moments M₀ and 2M₀ respectively, are fixed perpendicular to each other with their North poles in contact. The combination is placed on a floating body, so as to move freely in earth’s magnetic field, the value of a is

(a) tan-1(2)
(b) sin-1(1/2)
(c) cos-1(1/2)
(d) 20°

Question 19:
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
(a) MB
(b) √3MB/2
(c) MB/2
(d) zero

Question 20:
A tangent galvanometer of reduction factor 1A is placed with the plane of its coil parallel to the magnetic meridian, when a current of 1A is passed through it, the deflection produced is
(a) 45°
(b) zero
(c) 30°
(d) 60°

Question 21:
A bar magnet is suspended with unspun thread. It lies in the magnetic meridian. The upper end of the thread is turned through 150°. It turns the magnet by 30° with the magnetic meridian. Through what angle should the upper end of the thread be turned to rotate the magnet through 90°?
(a) 360°
(b) 330°
(c) 300°
(d) 270°

Question 22:
A uniform magnetic field parallel to the plane of paper, existed in space initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by figure

Question 23:
The variation of magnetic susceptibility (χ) with absolute temperature T for a ferromagnetic is given in figure, by

Question 24:
The permeability of the paramagnetic substance is
(a) very large
(b) small but more than 1
(c) less than 1
(d) negative

Question 25:
The susceptibility of the diamagnetic substance is
(a) very large
(b) positive and small
(c) zero
(d) negative

Question 26:
Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond curie temperature, then it will show
(a) paramagnetism
(b) anti-ferromagnetism
(c) no magnetic property
(d) diamagnetism

Question 27:
What is the relation between permeability μ, permeability of free space μ₀ and susceptibility χ_m?

Question 28:
Above Curie temperature
(a) a ferromagnetic substance becomes paramagnetic
(b) a paramagnetic substance becomes diamagnetic
(c) a diamagnetic substance becomes paramagnetic
(d) a paramagnetic substance becomes ferromagnetic

Question 29:
The magnetic susceptibility of a material of a rod is 499. Permeability of vacuum is 4π x10^-7 Hm^-1. Absolute permeability of the material of the rod in Hm-1 is
(a) π x 10^-4
(b) 2π x 10^-4
(b) 3π x 10^-4
(d) 4π x 10^-4

Question 30:
Hysteresis cycle for the material of permanent magnet should be
(a) long and wide
(b) long and thin
(c) short and wide
(d) short and thin

Question 31:
Which of the following is most suitable as the core of transformers?
(a) Steel
(b) Alinco
(c) Soft iron
(d) None of these

Direction (Q. Nos. 32-34): In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
(a) If both Assertion and Reason are true and Reason is not the correct explanation of Assertion
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Question 32:
Assertion (A): If a bar magnet is split parallel to its length in n parts, then magnetic moment of each part becomes 1/n times.
Reason (R): In this case the pole strength of each part remains as before but length becomes 1/n times.

Question 33:
Assertion (A): If the horizontal and vertical components of earth’s fields are equal at a certain place the angle of dip is 45°.
Reason (R): Angle of dip is zero at equator.

Question 34:
Assertion (A): Time period of oscillation of two magnets, when like poles are in same direction (in a vibration magnetometer) is smaller, than the period of vibration, when like poles are in opposite direction.
Reason (R): Moment of inertia increases in same position.

Question 35:
A coil in the shape of an equilateral triangle of side 0.02 m is suspended from its vertex, such that it is hanging in a vertical plane between the pole pieces of permanent magnet producing a uniform field of 5×10^-2T. If a current of 0.1 A is passed through the coil, what is the couple acting on it?
(a) 5√3 x 10^-7 Nm
(b) 5√3 x 10^-10 Nm
(c) √3/5 x 10^-7 Nm
(d) None of these

Question 36:
Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnets in different configurations. Each magnet has magnetic dipole moment m. Which configuration has highest net magnetic dipole moment?

(a) 1
(b) 2
(c) 3
(d) 4

Question 37:
When a proton is released from rest in a room, it starts with an initial acceleration a₀ towards West. When it is projected towards North with a speed v₀, it moves with an initial acceleration 3a₀ towards West. The electric and magnetic fields in the room are

Question 38:
A current loop in a magnetic field
(a) experiences a torque whether the field is uniform or non-uniform in all orientations
(b) can be in equilibrium in one orientation
(c) can be equilibrium in two orientations, both the equilibrium states are unstable
(d) can be in equilibrium in two orientations, one stable while the other is unstable

Question 39:
A bar magnet of length l and magnetic dipole moment M is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be

(a) M
(b) 3M/π
(c) 2M/π
(d) M/2

Question 40:
A uniform electric field and a uniform magnetic field are produced, pointed in the same direction. An electron is projected with its velocity pointing in the same direction
(a) the electron will turn to its left
(b) the electron will turn to its right
(c) the electron velocity will increase in magnitude
(d) the electron velocity will decrease in magnitude

Question 41:
A curve between magnetic moment and temperature of magnet is

Question 42:
Assertion (A): Susceptibility is defined as the ratio of intensity of magnetisation l to magnetic intensity H.
Reason (R): Greater the value of susceptibility smaller the value of intensity of magnetisation l.
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Question 43:
A North pole of 40 Am is placed 20 cm apart from a South pole of 80 Am. Calculate the distance of a point form the South pole on the line joining the two poles where the resultant field due to these poles is zero
(a) 8.2 cm towards North pole
(b) 8.2 cm away from North pole
(c) 48.2 cm towards North pole
(d) 48.2 cm away from North pole

Question 44:
At the magnetic pole of the earth, the value of angle of dip is
(a) 0°
(b) 30°
(c) 45°
(d) 90°

Question 45:
Two tangent galvanometer having coils of the same radius are connected in series. A current flowing in them, produces deflection of 60° and 45°, respectively. The ratio of the number of turns in the coils is
(a) 4/3
(b) (√3+1)/1
(c) √3/1
(d) (√3+1)/(√3-1)

Question 46:
Which one of the following is not made of soft iron?
(a) Electromagnet
(b) Core of transformer
(b) Core of dynamo
(d) Magnet of loudspeaker

Question 47:
Electromagnets are made of soft iron because soft iron has
(a) low retentivity and high coercive force
(b) high retentivity and high coercive force
(c) low retentivity and low coercive force
(d) high retentivity and low coercive force

Question 48:
A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with the time period of 2 s in earth’s horizontal magnetic field of 24 μT. When a horizontal field of 18 μT is produced opposite to the earth’s field by placing a current carrying wire, the new time period of magnet will be
(a) 1s
(b) 2s
(c) 3s
(d) 4s

Question 49:
A thin magnetic needle vibrates in the horizontal plane with a period of 4s. The needle is cut into two halves by a plane normal to magnetic axis of the needle. Then, the period of vibration of each half needle is approximately
(a) 4s
(b) 2s
(c) 8s
(d) 1s

Question 50:
Assertion (A): The magnetism of a magnet is due to the spin motion of electrons.
Reason (R): Dipole moment of electron is smaller than that due to orbitaf motion around nucleus.
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Answers:

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