MCQ in Electricity and Magnetism Fundamentals Part 13 | ECE Board Exam

This is the Multiple Choice Question Part 13 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 13 of the Series

Choose the letter of the best answer in each question.

601. Tesla is a unit of

A. field strength

B. inductance

C. flux density

D. flux

602. A permeable substance is one

A. which is a good conductor

B. which is a bad conductor

C. which is a strong magnet

D. through which the magnetic lines of force can pass very easily

603. The materials having low retentivity are suitable for making

A. weak magnets

B. temporary magnets

C. permanent magnets

D. none of the above

604. A magnetic field exists around

A. iron

B. copper

C. aluminium

D. moving charges

605. Ferrites are materials.

A. paramagnetic

B. diamagnetic

C. ferromagnetic

D. none of the above

606. Air gap has_______ reluctance as compared to iron or steel path

A. little

B. lower

C. higher

D. zero

607. The direction of magnetic lines of force is

A. from south pole to north pole

B. from north pole to south pole

C. from one end of the magnet to another

D. none of the above

608. Which of the following is a vector quantity?

A. Relative permeability

B. Magnetic field intensity

C. Flux density

D. Magnetic potential

609. The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is

A. proportional to 7

B. proportional to X

C. proportional to distance between the conductors

D. inversely proportional to I

610. A material which is slightly repelled by a magnetic field is known as

A. ferromagnetic material

B. diamagnetic material

C. paramagnetic material

D. conducting material

611. When an iron piece is placed in a magnetic field

A. the magnetic lines of force will bend away from their usual paths in order to go away from the piece

B. the magnetic lines of force will bend away from their usual paths in order to pass through the piece

C. the magnetic field will not be affected

D. the iron piece will break

612. Fleming’s left hand rule is used to find

A. direction of magnetic field due to current carrying conductor

B. direction of flux in a solenoid

C. direction of force on a current carrying conductor in a magnetic field

D. polarity of a magnetic pole

613. The ratio of intensity of magnetization to the magnetization force is known as

A. flux density

B. susceptibility

C. relative permeability

D. none of the above

614. Magnetizing steel is normally difficult because

A. it corrodes easily

B. it has high permeability

C. it has high specific gravity

D. it has low permeability

615. The left hand rule correlates to

A. current, induced e.m.f. and direction of force on a conductor

B. magnetic field, electric field and direction of force on a conductor

C. self induction, mutual induction and direction of force on a conductor

D. current, magnetic field and direction of force on a conductor

616. The unit of relative permeability is

A. henry/metre

B. henry

C. henry/sq. m

D. it is dimensionless

617. A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be

A. zero

B. BLI

C. B2LI

D. BLI2

618. The force between two long parallel conductors is inversely proportional to

A. radius of conductors

B. current in one conductor

C. product of current in two conductors

D. distance between the conductors

619. Materials subjected to rapid reversal of magnetism should have

A. large area of B-H loop

B. high permeability and low hysteresis loss

C. high coercivity and high retentivity

D. high coercivity and low density

620. Indicate which of the following material does not retain magnetism permanently.

A. Soft iron

B. Stainless steel

C. Hardened steel

D. None of the above

621. The main constituent of permalloy is

A. cobalt

B. chromium

C. nickel

D. tungsten

622. The use of permanent magnets is not made in

A. magnetoes

B. energy meters

C. transformers

D. loud-speakers

623. Paramagnetic materials have relative permeability

A. slightly less than unity

B. equal to unity

C. slightly more than unity

D. equal to that ferromagnetic mate rials

624. Degaussing is the process of

A. removal of magnetic impurities

B. removing gases from the materials

C. remagnetising metallic parts

D. demagnetising metallic parts

625. Substances which have permeability less than the permeability of free space are known as

A. ferromagnetic

B. paramagnetic

C. diamagnetic

D. bipolar

626. 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

A. 2 x 1(T2 N/m)

B. 2 x KT3 N/m

C. 2 x 10″5 N/m

D. 2x 1(T7 N/m)

627. In the left hand rule, forefinger always represents

A. voltage

B. current

C. magnetic field

D. direction of force on the conductor

628. Which of the following is a ferromagnetic material?

A. Tungsten

B. Aluminium

C. Copper

D. Nickel

629. Ferrites are a sub-group of

A. non-magnetic materials

B. ferro-magnetic materials

C. paramagnetic materials

D. ferri-magnetic materials

630. Gilbert is a unit of

A. electromotive force

B. magnetomotive force

C. conductance

D. permittivity

631. The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields

A. meter is surrounded by strong magnetic fields

B. a soft iron shielding is used

C. a plastic shielding is provided

D. a shielding of anon-magnetic material is used

632. Reciprocal of permeability is

A. reluctivity

B. susceptibility

C. permittivity

D. conductance

633. The relative permeability is less than unity is case of

A. ferromagnetic materials

B. ferrites

C. non-ferrous materials

D. diamagnetic materials

634. Which of the following is the unit of magnetic flux density?

A. weber

B. lumens

C. tesla

D. none of the above

635. The magnetism left in the iron after exciting field has been removed is known as

A. permeance

B. residual magnetism

C. susceptance

D. reluctance

636. Which of the following is not a unit of flux?

A. Maxwell

B. Telsa

C. Weber

D. All of the above

637. Which of the following is expected to have the maximum permeability?

A. Brass

B. Copper

C. Zinc

D. Ebonite

638. One tesla is equal to

A. 1 Wb/mm²

B. 1 Wb/m

C. 1 Wb/m²

D. 1 mWb/m²

639. Out of the following statements, concerning an electric field, which statement is not true ?

A. The electric intensity is a vector quantity

B. The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point

C. An electric field is defined as a point in space at which an electric charge would experience a force

D. Unit field intensity in the exertion of a force of one newton on a charge of one coulomb

640. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon

A. resistance of the coil

B. motion of the magnet

C. number of turns of the coil

D. pole strength of the magnet

641. One Maxwell is equal to

A. 10 Webers

B. 10 Webers

C. 10 Webers

D. 10 Webers

642. When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle

A. will be zero

B. will be infinite

C. will depend on the amount of e.m.f. applied

D. will depend on the radius of the circle

643. Susceptibility is positive for

A. non-magnetic substances

B. diamagnetic substances

C. ferromagnetic substances

D. none of the above

644. 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

A. 100 N

B. 10 N

C. 1 N

D. 0.1 N

645. A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be

A. 240 N

B. 24 N

C. 2.4 N

D. 0.24 N

646. A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is pivoted in a magnetic field having a flux density of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on the coil will be

A. 8 N-m

B. 0.48 N-m

C. 0.048 N-m

D. 0.0048 N-m

[Hint. Torque = 2BIlNr N-m]

647. The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength?

A. 2500 AT/m

B. 250 AT/m

C. 25 AT/m

D. 2.5 AT/m

648. What is the magnitude and the direction of force per 1.1 m length of a pair of conductors of a direct current line carrying 10 amperes and spaced 100 mm apart ?

A. 22 x 10⁸ N

B. 22 x 10⁷ N

C. 22 x 10^-6 N

D. 22 x 10⁵ N

649. A square cross-sectional magnet has a pole strength of 1 x 10^-3 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?

A. 63.38 N/Wb

B. 633.8 N/Wb

C. 6338 N/Wb

D. 63380 N/Wb

650. The unit of flux is the same as that of

A. reluctance

B. resistance

C. permeance

D. pole strength

Questions and Answers in Electricity and Magnetism Fundamentals

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