In the print window choose “Save as PDF”. The file prints without a web address or date line.
Mere Teacher · Previous Year Questions
NEET Physics · Magnetism & Matter · Set 4 (Q91-120)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
91.
Electromagnets are made of soft iron because soft iron has
(1)high susceptibility and low retentivity
(2)low susceptibility and high retentivity
(3)low susceptibility and low retentivity
(4)high susceptibility and high retentivity
92.
A 250‐turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85T. Work done for rotating the coil by 1800 against the torque is
(1)4.55 μJ
(2)2.3 μJ
(3)1.15 μJ
(4)9.1 μJ
93.
If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by μd,μp and μf respectively, then
(1)μd=0 and μp=0
(2)μd=0 and μp=0
(3)μp=0 and μf=0
(4)μd=0 and μf=0.
94.
Two bar magnets having same geometry with magnetic moments M and 2M, are firstly placed in such a way that their similar poles are in same side then its time period of oscillation is T1. Now the polarity of one of the magnet is reversed then time period of oscillation is T2, then
(1)T1<T2
(2)T1=T2
(3)T1>T2
(4)T2=∞
95.
A paramagnetic sample shows a net magnetisation of 6A/m when it is placed in an external magnetic field of 0.4T at a temperature of 4K. When the sample is placed in an external magnetic field of 0.3T at a temperature of 24K, then the magnetisation will be
(1)1A/m
(2)0.75A/m
(3)4A/m
(4)2.25A/m
96.
Magnetic susceptibility (χ) for a paramagnetic and diamagnetic materials is respectively
(1)small, positive and small, positive
(2)large, positive and small, negative
(3)small, positive and small, negative
(4)large, negative and large, positive.
97.
A short bar magnet placed with its axis at 45∘ with a uniform external magnetic field of 28.3×10−3T experiences a torque of magnitude equal to 3.6×10−5J. The magnitude of magnetic moment of the magnet is nearly
(1)1.8×10−3JT−1
(2)1.2×10−3JT−1
(3)2.4×10−3JT−1
(4)1.6×10−3JT−1
98.
A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 secin earth’s horizontal magnetic field of 24 microtesla. When a horizontal field of 18 microtesla is produced opposite to the earth’s field by placing a current carrying wire, the new time period of magnet will be
(1)1 s
(2)2 s
(3)3 s
(4)4 s
99.
An iron rod is placed parallel to magnetic field of intensity 2000A/m. The magnetic flux through the rod is 6×10−4Wb and its cross-sectional area is 3cm2. The magnetic permeability of the rod in Wb/A−m is
(1)10−1
(2)10−2
(3)10−3
(4)10−4
100.
If B is magnetic field and q is the charge then the following represents the Gauss's law of magnetism
(1)∫B⋅ds=0
(2)∫B⋅ds=q
(3)∫B⋅ds=4π
(4)∫B⋅ds=μ0q
101.
An object is located at 2km beneath the surfaceof the water. If the fractional compression VΔV is 1.36%, the ratio of hydraulic stress to the corresponding hydraulic strain will be [Given: density of water is 1000kgm−3 and (g=9.8ms−2⋅)
(1)1.96×107Nm−2
(2)1.44×107Nm−2
(3)2.26×109Nm−2
(4)1.44×109Nm−2
102.
The pressure acting on a submarine is 3×105Pa at a certain depth. If the depth is doubled, the percentageincrease in the pressure acting on the submarine would be : (Assume that atmospheric pressure is 1×105Padensity of water is (103kgm−3,g=10ms−2)
(1)3200%
(2)5200%
(3)2005%
(4)2003%
103.
The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation:
(1)Phase
(2)Intensity
(3)Amplitude
(4)Frequency
104.
An iron rod of susceptibility 599 is subjected to a magnetizing field of 1200Am−1. The permeability of the material of the rod is (Take, μ0=4π×10−7TmA−1) [NEET 2020]
(1)8.0×10−5TmA−1
(2)24π×10−5TmA−1
(3)2.4π×10−7TmA−1
(4)2.4π×10−4TmA−1
105.
A bar magnet of magnetic moment M is cut into two parts of equal length. The magnetic moment of each part will be
(1)M
(2)2M
(3)zero
(4)0. 5M
106.
The magnetic moment of a bar magnet is 0.5Am2. It is suspended in a uniform magnetic field of 8×10−2T. The work done in rotating it from its most stable to most unstable position is:
(1)8×10−2J
(2)4×10−2J
(3)Zero
(4)16×10−2J
107.
The axial field (BA) and the equatorial field (BE) due to a short bar magnet at equal distances are related as
(1)BA=2BE
(2)BA=−2BE
(3)BA=−BE
(4)BA=−2πBE
108.
The magnitude of axial field due to a bar magnet at a distance of 1m, is found to be 5×10−8T. The magnetic moment of the bar magnet is (μ0=4π×10−7)
(1)0.20Am2
(2)0.25Am2
(3)0.50Am2
(4)0.40Am2
109.
A steel wire having a radius of 2.0 mm, carrying a load of 4 kg, is hanging from a ceiling. Given that g=3.1πms–2, what will be the tensile stress that would be developed in the wire?
(1)6.2×106Nm−2
(2)5.2×106Nm−2
(3)3.1×106Nm−2
(4)4.8×106Nm−2
110.
A bar magnet has length 3cm, cross-sectional area 2cm2 and magnetic moment 3Am2. The intensity of magnetisation of bar magnet is
(1)2×105A/m
(2)4×105A/m
(3)3×105A/m
(4)5×105A/m
111.
A solenoid has a core of a material with relative permeability 501. The windings of the solenoid are insulated from the core and carry a current of 2.5 A. If the number of turns are 900 per meter. The magnetisation (in A/m) is
(1)1.12×106
(2)2.8×106
(3)2.25×106
(4)1.69×106
112.
Magnetic materials used for making permanent magnets (P) and magnets in a transformer (T) have different properties of the following, which property best matches for the type of magnet required?
(1)T:Large retentivity, small coercivity
(2)P:Large retentivity, large coercivity
(3)P: Small retentivity, large coercivity
(4)T:Large retentivity, large coercivity
113.
A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains:
(1)decrease in size and changes orientation.
(2)may increase or decrease in size and change its orientation.
(3)increase in size but no change in orientation.
(4)have no relation with external magnetic field
114.
When two soap bubbles of radii a and b(b>a) coalesce, the radius of curvature of common surface is:
(1)b−aab
(2)aba+b
(3)abb−a
(4)a+bab
115.
A bar magnet having a magnetic moment of 2×104JT−1 is free to rotate in a horizontal plane. A horizontal magnetic field B=6×10−4T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60o from the field is
(1)12J
(2)6J
(3)2J
(4)0.6J
116.
If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is
(1)repelled by the north pole and attracted by the south pole
(2)attracted by the north pole and repelled by the south pole
(3)attracted by both the poles
(4)repelled by both the poles
117.
A magnet hung at 45° with magnetic meridian makes an angle of 60° with the horizontal. The actual value of the angle of dip is
(1)tan−1(23)
(2)tan−1(6)
(3)tan−1(32)
(4)tan−1(21)
118.
Core of electromagnets are made of ferromagnetic material which has
(1)high permeability and high retentivity
(2)low permeability and low retentivity
(3)high permeability and low retentivity
(4)low permeability and high retentivity.
119.
The force acting per unit length when a very long straight conductor is carrying a steady current of 1A and the direction of the current is from south to north is (The horizontal component of the earth's magnetic field at the place is 3×10−5T and the direction of the field is from the geographical south to geographical north.)
(1)3×10−5Nm−1
(2)1×10−5Nm−1
(3)0
(4)1.5×10−5Nm−1
120.
A rod, of length L at room temperature and uniform area of cross section A, is made of a metal having a coefficient of linear expansion α/℃. It is observed that an external compressive force F, is applied on each of its ends, prevents any change in the length of the rod, when its temperature rises by ΔTK. Young's modulus, Y, for this metal is:
