MCQ in Electricity and Magnetism Fundamentals Part 14 | ECE Board Exam

This is the Multiple Choice Question Part 14 of the Series in Electricity and Magnetism Fundamentals as one of the Electronics Engineering topics. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every question compiled here taken from various sources including but not limited to past Board Exam Questions in the Electronics Engineering field, Electronics Books, Journals and other Electronics References.

MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQ in Atomic Structure
• MCQ in Electric Charge
• MCQ in Ohm’s Law, Kirchhoff Law, Coulomb’s Law, etc
• MCQ in Magnetic Power
• MCQ in Magnetic Field and Magnetic Flux
• MCQ in Magnetic and Electric Quantities / Units
• MCQ in Magnetic/Electromagnet Principles

Continue Practice Exam Test Questions Part 14 of the Series

Choose the letter of the best answer in each question.

651. Unit for quantity of electricity is

A. ampere-hour

B. watt

C. joule

D. coulomb

652. The Biot-savart’s law is a general modification of

A. Kirchhoff’s law

B. Lenz’s law

C. Ampere’s law

D. Faraday’s laws

653. The most effective and quickest may of making a magnet from soft iron is by

A. placing it inside a coil carrying current

B. induction

C. the use of permanent magnet

D. rubbing with another magnet

654. The commonly used material for shielding or screening magnetism is

A. copper

B. aluminium

C. soft iron

D. brass

655. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity

A. less than that of disc but in opposite direction

B. equal to that of disc and in the same direction

C. equal to that of disc and in the opposite direction

D. less than that of disc and in the same direction

656. A permanent magnet

A. attracts some substances and repels others

B. attracts all paramagnetic substances and repels others

C. attracts only ferromagnetic substances

D. attracts ferromagnetic substances and repels all others

657. The retentivity (a property) of material is useful for the construction of

A. permanent magnets

B. transformers

C. non-magnetic substances

D. electromagnets

658. The relative permeability of materials is not constant.

A. diamagnetic

B. paramagnetic

C. ferromagnetic

D. insulating

659. The materials are a bit inferior conductors of magnetic flux than air.

A. ferromagnetic

B. paramagnetic

C. diamagnetic

D. dielectric

660. Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials.

A. circular

B. triangular

C. rectangular

D. none of the above

661. A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be

A. M

B. M/2

C. 2 M

D. M/4

662. A keeper is used to

A. change the direction of magnetic lines

B. amplify flux

C. restore lost flux

D. provide a closed path for flux

663. Magnetic moment is a

A. pole strength

B. universal constant

C. scalar quantity

D. vector quantity

664. The change of cross-sectional area of conductor in magnetic field will affect

A. reluctance of conductor

B. resistance of conductor

C. A. and B. both in the same way

D. none of the above

665. The uniform magnetic field is

A. the field of a set of parallel conductors

B. the field of a single conductor

C. the field in which all lines of magnetic flux are parallel and equidistant

D. none of the above

666. The magneto-motive force is

A. the voltage across the two ends of exciting coil

B. the flow of an electric current

C. the sum of all currents embraced by one line of magnetic field

D. the passage of magnetic field through an exciting coil

667. What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200?

A. 2

B. 4

C. 6

D. 8

668. What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m ?

A. 2 AT

B. 4 AT

C. 6 AT

D. 10 AT

669. Which of the following statements is correct?

A. The magnetic flux inside an exciting coil is lower than its outside surface

B. The magnetic flux inside an exciting coil is zero

C. The magnetic flux inside the exciting coil is greater than its outside surface

D. The magnetic flux inside the exciting coil is same as on its outside surface

670. A certain amount of current flows through a ring-shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil ?

A. Decreases

B. Increases

C. Remains same

D. First increases and then decreases depending on the depth of iron insertion

671. The magnetic reluctance of a material

A. decreases with increasing cross sectional area of material

B. increases with increasing cross-sectional area of material

C. does not vary with increasing cross-sectional area of material

D. any of the above

672. The initial permeability of an iron rod is

A. the highest permeability of the iron rod

B. the lowest permeability of the iron rod

C. the permeability at the end of the iron rod

D. the permeability almost in non-magnetized state

673. How does the magnetic compass needle behave in a magnetic field ?

A. It assures a position right angle to magnetic field

B. It starts rotating

C. It assures a position which follows a line of magnetic flux

D. None of the above

674. In a simple magnetic field the strength of magnet flux

A. is constant and has same value in energy part of the magnetic field

B. increases continuously from initial value to final value

C. decreases continuously from initial value to final value

D. first increases and then decreases till it becomes zero

675. The stray line of magnetic flux is defined as

A. a line vertical to the flux lines

B. the mean length of a ring shaped coil

C. a line of magnetic flux in a non-uniform field

D. a line of magnetic flux which does not follow the designed path

676. The bar magnet has

A. the dipole moment

B. monopole moment

C. both A. and B. 

D. none of the above

677. Which of the following materials are diamagnetic?

A. Silver

B. Copper

C. Silver and copper

D. Iron

678. Which of the following type of materials are not very important for engineering applications?

A. Ferromagnetic

B. Paramagnetic

C. Diamagnetic

D. None of the above

679. The susceptibility of paramagnetic materials generally lies between

A. KT3 and 1CT6

B. 1CT3 and 1CT7

C. KT4 and KT8

D. 10″2 and KT5

680. For which of the following materials the saturation value is the highest ?

A. Ferromagnetic materials

B. Paramagnetic materials

C. Diamagnetic materials

D. Ferrites

681. The magnetic materials exhibit the property of magnetization because of

A. orbital motion of electrons

B. spin of electrons

C. spin of nucleus

D. either of these

E.  all of the above

682. For which of the following materials the net magnetic moment should be zero ?

A. Diamagnetic materials

B. Ferrimagnetic materials

C. Antiferromagnetic materials

D. Antiferromagnetic materials

683. The attraction capacity of electromagnet will increase if the

A. core length increases 

B. core area increases

C. flux density decreases

D. flux density increases

684. Which of the following statements is correct ?

A. The conductivity of ferrites is better than ferromagnetic materials

B. The conductivity of ferromagnetic materials is better than ferrites

C. The conductivity of ferrites is very high

D. The conductivity of ferrites is same as that of ferromagnetic materials

685. Temporary magnets are used in

A. loud-speakers

B. generators

C. motors

D. all of the above

686. Main causes of noisy solenoid are

A. strong tendency of fan out of laminations at the end caused by repulsion among magnetic lines of force

B. uneven bearing surface, caused by dirt or uneven wear between moving and stationary parts

C. both of above

D. none of the above

687. Strength of an electromagnet can be increased by

A. increasing the cross-sectional area

B. increasing the number of turns

C. increasing current supply

D. all above methods

688. Core of an electromagnet should have

A. low coercivity

B. high susceptibility

C. both of the above

D. none of the above

689. Magnetism of a magnet can be destroyed by

A. heating

B. hammering

C. by inductive action of another magnet

D. by all above methods

Questions and Answers in Electricity and Magnetism Fundamentals

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