Electricity and Magnetism Practice Quiz 08

Electricity and Magnetism Practice Quiz 08

Welcome to ECE Board Exam Practice Quiz for Electricity and Magnetism Fundamentals. This set of practice quiz 8 will test your competence on the theories, concepts and problem solving involving Electricity and Magnetism. The objectives and goals of this quiz is to help engineering students familiarize concepts and theories as well as develop problem solving skills when answering questions related to the Electricity and Magnetism Fundamentals.

Electricity and Magnetism Test Bank

In this section are compiled practice quiz for Electricity and Magnetism that could be able to enhance your knowledge and skills in your preparation for the ECE Board Exam. The goal is to add thousands of questions for you to be familiarized and hopefully help you to be prepared. I am looking forward that this practice quiz will give you an additional confidence in taking your upcoming Engineering Board Exam.

Guidelines:
  • Read and understand each question before choosing the best answer.
  • The correct answer will be reveal after you have chosen your answer for every questions
  • There is no time limit, answer the questions at your own pace.
  • Once all questions are answered, you will be shown your rating.
  • You have to get 70% of the total items to pass the quiz.
  • You can re-take the quiz as many times as you want or until you are satisfied of your rating.
  • Comment us your thoughts, scores, ratings, and questions about the quiz in the comments section below!

Choose the letter of the best answer in each questions.

The B-H curve for ______ is a straight line passing through the origin.
cobalt
air
hardened steel
soft iron

Correct!

Wrong!

In electro-mechanical conversion devices like generators and motors the reason why a small air gap is left between the rotor and stator is to
permit mechanical clearance
increase flux density in air gap
decrease the reluctance of magnetic path
complete the magnetic path

Correct!

Wrong!

A 6 V battery is connected across a solenoid of 100 turns having a resistance of 2 Ω, Calculate the number of ampere turns?
100
50
300
600

Correct!

Wrong!

A magnetic field is
The current flow through space around a permanent magnet
The force set up when current flows through a conductor
The force that drives current through a resistor
The force between the plates of a charged capacitor

Correct!

Wrong!

Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10-6 T/A.t/m
0.252 G
0.252 x 10^-2 T
0.252 T
0.252 x 10^-2 G

Correct!

Wrong!

The conduction of electricity across the surface of a dielectric is called
creepage
skin effect
surface effect
crosstalk

Correct!

Wrong!

Back emf refers to the
Current equal to the applied emf
Opposing emf
Current opposing the applied emf
Voltage opposing the applied emf

Correct!

Wrong!

A law stating that the magnetic susceptibilities of most paramagnetic substances are inversely proportional to their absolute temperatures.
Curie’s Law
Child’s Law
CR Law
Curie-Weiss Law

Correct!

Wrong!

One of the solid structures in which the position of the atoms or ions are predetermined
Crystalline solid
Amorphous solid
Polycrystalline solid
Poly-amorphous solid

Correct!

Wrong!

Defined as the ratio of the volume occupied by the atoms or ions in a unit cell divided by the volume of the unit cell and is used to measure the compactness of a crystal.
Atomic packing factor (APF)
Ionic Packing Ratio (IPR)
Atomic compacting factor (ACF)
Ionic compacting ratio (ICR)

Correct!

Wrong!

What is the SI unit of reluctance?
At
At/m
N/Wb
At/Wb

Correct!

Wrong!

The reluctance of a magnetic circuit is not dependent on which of the following?
Number of turns of coil
Magnetomotive force
Flux density in the circuit
Current in the coil

Correct!

Wrong!

What is the reluctance of a magnetic path having a length of 2 x 10-3 m and cross- sectional area of 2.5 x 10-3 m2?
6366 A.t/Wb
6000 A.t/Wb
8 x 10^-3 A.t/Wb
0.8 A.t/Wb

Correct!

Wrong!

The B-H curve of _______ is not a straight line.
air
wood
silicon steel
soft iron

Correct!

Wrong!

Which of the following materials has the least hysteresis loop area?
soft iron
silicon steel
hard steel
wrought iron

Correct!

Wrong!

When the current flows, the magnetic field conductor is in what direction?
The same as the current direction
Opposite the current direction
Omnidirectional
In the direction determined by the left hand rule

Correct!

Wrong!

Hysteresis loss can be reduced by one of the following.
Increasing mmf of the circuit
Using material narrow hysteresis loop
Using ferromagnetic core
Laminating the magnetic circuit

Correct!

Wrong!

A principle that states that only two electrons with different spins are allowed to exist in a given orbit
Bohr’s principle
Pauli exclusion principle
Avogadro’s principle
Coulomb’s principle

Correct!

Wrong!

Permeance of a magnetic circuit is ________ the cross-sectional area of the circuit.
directly proportional to
inversely proportional to
dependent of
independent of

Correct!

Wrong!

A law relating between the magnetic and electric susceptibilities and the absolute temperatures which is followed b ferromagnets, antiferromagnets, non-polar ferroelectrics, antiferroelectric and some paramagnets.
Curie’s Law
Child’s Law
CR Law
Curie-Weiss Law

Correct!

Wrong!

A magnetic flux of 2.5 x 104 Wb through an area of 5 x 104 square meters results in
5 Wb
0.5 Tesla of flux density
5 x 10^-5 Wb of flux
5000 Tesla of flux density

Correct!

Wrong!

What solid has no defined crystal structure except perhaps in the arrangement of the nearest neighboring atoms or ions?
Crystalline
Amorphous
Polycrystalline
Poly-amorphous

Correct!

Wrong!

What is the usual value of leakage coefficient for electrical machines?
0.5 to 1
1 to 5
5 to 10
1.15 to 1.25

Correct!

Wrong!

Why is it that the magnitude of magnetomotive force required for air gap is much greater than that required for iron part of a magnetic circuit?
Because air is a gas
Because air has the highest relative permeability
Because air is a conductor of magnetic flux
Because air has the lowest relative permeability

Correct!

Wrong!

The reluctance of a magnetic circuit varies with
length × area
area ÷ length
length ÷ area
length + area

Correct!

Wrong!

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