Magnetism And Electromagnetism — Part 1 MCQs with Explanations

Explanation: Maxwell is a unit of magnetic flux in the CGS (centimeter-gram-second) system of units. 1 maxwell is equivalent to 10 -8 webers in the SI (International System of Units). Reason: The relation between the CGS and SI units of magnetic flux is established as: 1 weber = 10 8 maxwells Hence, 1 maxwell = 10 -8 webers.

Option A: Ferromagnetic - Ferromagnetic materials (like iron) are strongly attracted to magnets. They can also become permanently magnetized. Think of things like transformers, motors, and hard drives. They're very important in electrical engineering. Option B: Paramagnetic - Paramagnetic materials are weakly attracted to magnets. This attraction disappears when the external magnetic field is removed. They have some engineering applications, but they are not as widely used as ferromagnetic material. Option C: Diamagnetic - Diamagnetic materials are actually repelled by magnets (though very weakly). This repulsion also disappears when the external magnetic field is removed. They have very limited engineering applications compared to the other types. Option D: None of the above - This suggests that all the materials are important, which is incorrect. Therefore, the correct answer is Option C: Diamagnetic . Diamagnetic materials aren't as critical in many common engineering applications compared to ferromagnetic and, to a lesser extent, paramagnetic materials.

Magnetic materials exhibit the property of magnetization due to the orbital motion of electrons and the spin of electrons . The orbital motion of electrons around the nucleus generates a small magnetic field, contributing to the overall magnetization of the material. The spin of electrons also creates a magnetic moment, which plays a crucial role in determining the magnetic properties of the material. Though the spin of the nucleus can contribute to magnetism, its effect is negligible compared to electron motion and spin. Since magnetization can result from either the orbital motion of electrons or the spin of electrons , the correct answer is Option D: Either of These.

The air gap in a magnetic circuit has higher reluctance compared to the iron or steel path. Reluctance is the opposition to the flow of magnetic flux, similar to resistance in an electrical circuit. Since air has a much lower magnetic permeability than iron or steel, the reluctance of an air gap is significantly higher. In contrast, iron and steel have high permeability, allowing them to conduct magnetic flux easily with very low reluctance. Hence, the correct answer is Higher (Option C).

24 At is the correct answer to “What is the magneto-motive force (mmf) of a wire with 8 turns carrying three amperes of current”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

by all above methods is the correct answer to “Magnetism of a magnet can be destroyed by”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

all above methods is the correct answer to “Strength of an electromagnet can be increased by”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

300 At is the correct answer to “What is the magneto-motive force in a 75-turn coil of wire when there are 4 A of current through it”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

moving charges is the correct answer to “A magnetic field exists around”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

4 AT is the correct answer to “What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

the magnetic lines of force will bend away from their usual paths in order to pass through the piece is the correct answer to “When an iron piece is placed in a magnetic field”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

all of the above is the correct answer to “Temporary magnets are used in”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Telsa is the correct answer to “Which of the following is not a unit of flux”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

residual magnetism is the correct answer to “The magnetism left in the iron after exciting field has been removed is known as”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

temporary magnets is the correct answer to “The materials having low retentivity are suitable for making”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

permanent magnets is the correct answer to “The retentivity (a property) of material is useful for the construction of”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Is zero is the correct answer to “If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

pole strength is the correct answer to “The unit of flux is the same as that of”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

provide a closed path for flux is the correct answer to “A keeper is used to”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

attracts some substances and repels others is the correct answer to “A permanent magnet”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

2x 1(T7 N/m) is the correct answer to “Two infinitely long parallel conductors in vacuum any separated 1 metre between centers >then a current of 1 ampere flows the. uk each conductor, produce on each other a force of”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Decrease is the correct answer to “A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

high permeability and low hysteresis loss is the correct answer to “Materials subjected to rapid reversal of magnetism should have”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

rectangular is the correct answer to “Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials.”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

ferromagnetic is the correct answer to “The relative permeability of materials is not constant.”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

through which the magnetic lines of force can pass very easily is the correct answer to “A permeable substance is one”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

a line of magnetic flux which does not follow the designed path is the correct answer to “The stray line of magnetic flux is defined as”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

will depend on the radius of the circle is the correct answer to “When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

0.1 N is the correct answer to “Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

decreases with increasing cross sectional area of material is the correct answer to “The magnetic reluctance of a material”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

current, magnetic field and direction of force on a conductor is the correct answer to “The left hand rule correlates to”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Resistance of the coil is the correct answer to “When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Diamagnetic is the correct answer to “Substances which have permeability less than the permeability of free space are known as”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

6338 N/Wb is the correct answer to “A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

slightly more than unity is the correct answer to “Paramagnetic materials have relative permeability”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

first increases and then decreases till it becomes zero is the correct answer to “In a simple magnetic field the strength of magnet flux”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Antiferromagnetic materials is the correct answer to “For which of the following materials the net magnetic moment should be zero”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Increases the flux density is the correct answer to “For a given wire-wound core, an increase in current through the coil”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

magnetic field is the correct answer to “In the left hand rule, forefinger always represents”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.

Ampere's law is the correct answer to “The Biotsavart's law is a general modification of”. This question is standard in competitive examination syllabi for Magnetism And Electromagnetism.