Quiz-16-magnetic-effect-of-current-&-magnetism

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MAGNETISM AND MATTER Quiz-16

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 magnet makes 5 oscillations per min in B=0.3×10^-4T. By what amount should the field be increased so that number of oscillations is 10 in the same time?

•  0.3×10^-4T
•  0.6 ×10^-4T
•  0.9 ×10^-4T
•  1.2 ×10^-4T

Solution

Q2. The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be

•  2 s
•  2/3 s
•  2√3 s
•  2/√3 s

Solution
The time period of oscillations of magnet 

Q3. The mass of specimen of a ferromagnetic material is 0.6 kg and the density is 7.8×10³ kg m^-3. If the area of hysteresis loop of alternating magnetizing field of frequency 50 Hz is 0.722 MKS units, then hysteresis loss per second will be

•  27.77×10^-5 J
•  2.777 ×10^-5 J
•  27.27 ×10^-4 J
•  27.77 ×10^-6 J

Solution
If V=volume of the material = mass/density A= area of hysteresis loop v= frequency of alternate magnetic field applied t= time for which field is applied Then, energy loss in the material in t second is 

Q4. A small bar magnet has a magnetic moment 1.2 A-m². The magnetic field at a distance 0.1 m on it axis will be: (μ₀=4π×10^-7-m/A)

•  1.2×10^-4 T
•  2.4×10^-4 T
•  2.4×10⁴ T
•  1.2×10⁴ T

Solution

Q5.Unit of magnetic flux density (or magnetic induction) is

•  Tesla
•  Weber/metre²
•  Newton/ampere-metre
•  All of the above

Solution
 It is a fact.

Q6. Force between two identical short bar magnets whose centers are r metre apart is 8.1 N, when their axes are along the same line. If separation is increased to 3 r and the axis are rearranged perpendicularly, the force between them would become

•  2.4 N
•  1.2 N
• 0.1 N
•  1.15 N

Solution

Q7.A magnetic needle suspended horizontally by an unspun silk fibre, oscillates in the horizontal plane because of the restoring force originating mainly from

•  The torsion of the silk fibre
•  The force of gravity
•  The horizontal component of earth’s magnetic field
•  All of the above factors

Solution

Q8.The magnetic potential at a point on the axial line of a bar magnet of dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment M/4 at the same point

•  4 V
•  2V
•  V/2
•  V/4

Solution
Magnetic potential at a distance d from the bar magnet on it’s axial line is given by 

Q9.The sensitivity of a tangent galvanometer is increased if

•  Number of turn decreases
•  Number of turn increases
•  Field increases
•  None of the above

Solution

For increasing sensitivity K should be decreased and hence number of turns should be increased

Q10. Which of the following relations is correct in magnetism

•  I²=V²+H²
•  I=V+H
•  V=I²+H²
• V²=I+H

Solution
It is a fact.