Quiz-13-magnetic-effect-of-current-&-magnetism

C

MAGNETISM AND MATTER Quiz-13

Dear Readers,

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background. Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. .

Q1. 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 2^2/5s. One of the magnets is removed and if the other magnet oscillates in the same field , then the time period in second is

•  2^1/4
•  2^1/2
•  2
•  4

Solution
When two identical bar magnets are held perpendicular to each other.

Q2. If a magnet is hanged with its magnetic axis then it stops in

•  Magnetic meridian
•  Geometric meridian
•  Angle of dip
•  None of these

Solution

Q3. Needles N₁,N₂ and N₃ are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will

•  Attract N₁ andN₂ strongly but reple N₃
•  Attract N₁ strongly, N₂ weakly and reple N₃ weakly
•  Attract N₁ strongly, but reple N₂ and N₃ weakly
•  Attract all three of them

Solution
Ferromagnetic substance have strong tendency to get magnetized (induced magnetic moment) in the same direction as that of applied magnetic field, so magnet attract N₁ strongly. Paramagnetic substances get weakly magnetized (magnetic moment induced is small) in the same direction as that of applied magnetic field, so magnet attracts N₂ weakly. Diamagnetic substances also get weakly magnatised when placed in an external magnetic field but in opposite direction and hence, N₃, is weakly repelled by magnet.

Q4. Two lines of force due to a bar magnet

•  Intersect at the neutral point
•  Intersect near the poles of the magnet
•  Intersect on the equatorial axis of the magnet
•  Do not intersect at all

Solution
It is a fact.

Q5.At a certain place, the angle of dip is 30° and the horizontal component of earth’s magnetic field is 0.50 oersted. The earth’s total magnetic filed (in oersted) is

•  √3
•  1
•  1/√3
•  1/2

Solution
 R= H/cosδ=0.50/(cos30°)=(0.50×2)/√3=1/√3

Q6. A vibration magnetometer is placed at south pole, then the time period will be

•  Zero
•  Infinity
• Same as at magnetic equator
•  Same as at any other place on earth

Solution
At south pole, H=0 T=2π√(1/MH= ) ∞

Q7.Iron would become paramagnetic at about

•  200℃
•  400℃
•  600℃
•  800℃

Solution
It is a fact.

Q8.The earth’s magnetic field at a certain place has a horizontal component 0.3 gauss and the total strength 0.5 gauss. The angle of dip is

•  tan^-13/4
•  sin^-13/4
•  tan^-14/3
•  sin^-13/5

Solution

Q9.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^-2 T. If a current of 0.1 A is passed through the coil, what is the couple acting

•  5√3×10^-7 N-m
•  5√3×10^-10 N-m
•  √3/5×10^-7 N-m
•  None of these

Solution

Q10. Curie’s law can be written as

•  χ∝(T-T_c)
•  χ∝ 1/(T-T_c )
•  χ∝ 1/T
• χ∝T

Solution
It is a fact.