4001 ELECS - FIRST 450 QUESTIONS

Question 1

What physical effect will two parallel wires and with the same direction of current flowing over them

Answer 1

Attract each other

Question 2

The ratio between the intensity of magnetization produced in a substance, to the source of magnetizing force

Answer 2

magnetic susceptibility

Question 3

magnetic susceptibility (X) formula?

Answer 3

X = M / H
- intensity of magnetization
- source of magnetizing force, magnetic field intensity

Question 5

intensity of magnetization formula

Answer 5

M = m / V
- m is magnetic moment
- V is volume of material

Question 6

magnetic moment formula, 2 formulas

Answer 6

m = I x A
m = qvR / 2

Question 7

source of magnetization is? formula?

Answer 7

magnetic field intensity, mmf / l

Question 8

The motion of charged particles especially colloidal particles through a stationary liquid under the influence of applied electric fields provided

Answer 8

Electrophoresis

Question 9

What physical motion results from the forces of magnetic fields?

Answer 9

motor action

Question 10

the term describes a material whose resistance remains relatively constant with changes in the temperature

Answer 10

zero temperature coefficient

Question 11

which of the following is the resulting effect when electron is made to move?

Answer 11

dynamic electricity

Question 12

one of the following characteristics of a resistive material which do not change its resistive value with respect to time is its ____.

Answer 12

stability

Question 13

the time lag of the magnetic flux in a magnetic material, behind the magnetizing force producing it caused by the molecular friction of the molecules trying to allow themselves with the magnetic force applied to the material.

Answer 13

Hysteresis

When you apply a magnetic field, the magnetic domains inside the material don’t immediately align with it because of this internal molecular friction. This causes a lag between the applied magnetizing force and the resulting magnetic flux. This lag and retention of magnetization even after the field is removed is what we call hysteresis

Question 14

What quantity of magnetizing is needed to counterbalance the residual magnetism of a magnetic material?

Answer 14

Coercivity is the amount of magnetizing force required to reduce the residual magnetism (or remanence) of a magnetic material to zero

Question 15

measures the resistance of a material to becoming demagnetized

Answer 15

coercivity

Question 16

the amount needed to demagnetize a magnet?

Answer 16

coercivity

Question 17

What do you call the magnetic force left in a magnetic material after magnetic induction?

Answer 17

residual magnetism

Question 18

other term for residual magnetism?

Answer 18

remanence

Question 19

what do you call the flux that does not follow the intended path in a magnetic circuit?

Answer 19

leakage flux

Question 20

group of magnetically aligned atoms?

Answer 20

domain

Question 21

the science of physical phenomena at very low temperature, approaching absolute zero, is called?

Answer 21

cryogenics

Question 22

Theory in magnetism that assumes that all magnetic materials is composed of many tiny magnets?

Answer 22

Weber Theory

Question 23

What is used to maintain strength of magnetic field?

Answer 23

keeper

Question 24

what is used to focus the magnetic flux?

Answer 24

core

Question 25

when talking about maintaining magnetic field strength we're talking about ________. when we're talking about directing magnetic flux resulting to increase in flux density and magnetic field strength, we're talking about_______.

Answer 25

keeper, core

Question 26

the magnetism remaining in a substance or material after the removal of the magnetizing force

Answer 26

residual magnetism

Question 27

power rating of carbon-composition resistors?

Answer 27

1/8 to 2 watts

Question 28

general power rating of all resistors?

Answer 28

1/8 to 5 watts

Question 29

most common resistors? what are their colors?

Answer 29

carbon - film and metal - film brown and blue respectively

Question 30

Material that changes directly from solid to liquid with no plastic or semi-liquid state?

Answer 30

Eutectic alloy

Question 31

the definite discrete amount of energy required to move an electron from a lower shell to higher shell?

Answer 31

quanta

Question 32

the transfer of energy from one circuit to another circuit by electromagnetic induction is called?

Answer 32

transformer action

Question 33

the concept whereby a small voltage is generated by a conductor with current in an external magnetic field refers to _______.

Answer 33

hall effect

Question 34

loss of electrical energy in counterbalancing the residual magnetism in each cycle is called _____.

Answer 34

hysteresis loss

Question 35

how do you demagnetize properly?

Answer 35

apply and AC field and then gradually reduce it to zero

Question 36

what do you call when you properly demagnetize a magnet?

Answer 36

degaussing

Question 37

refers to a force of field that exists between ions where they either repel or attract each other

Answer 37

potential field

Question 38

what is called the flux density produced within, due to its own induced magnetism?

Answer 38

magnetic field intensity

Question 39

what component of dielectric current is proportional to the rate of accumulation of electric charges within the dielectric?

Answer 39

absorption current

Question 40

who invented the first electrical instrument used to help gauge the ability of objects to attract, called versorium?

Answer 40

william gilbert

Question 41

first electroscope, a device used to detect the presence of static electric charge

Answer 41

versorium

Question 42

device used to detect static charges?

Answer 42

electroscope

Question 43

typical resistivity range of conductors

Answer 43

10^-6 to 10^-4 ohm-cm

Question 44

typical resistivity range of semiconductors?

Answer 44

10^-4 to 10^9 ohm-cm

Question 45

typical resistivity range of insulators?

Answer 45

10^9 to 10^25 ohm-cm

Question 46

what is the first capacitor?

Answer 46

Leyden Jar

Question 47

who invented the Leyden Jar?

Answer 47

Pieter van Musschenbroek

Question 48

what is the replacement of Leyden Jar?

Answer 48

Electrophorus

Question 49

who invented the electrophorus?

Answer 49

Alessandro Volta

Question 49

nonmetallic materials that have ferromagnetic properties?

Answer 49

ferrites

Question 50

________ materials have magnetic moments that align in opposite directions, but not equally, so there's a net magnetization

Answer 50

ferrimagnetic

Question 51

ferrites are made of what material?

Answer 51

ceramic

Question 52

typical relative permeability of ferrite

Answer 52

50 - 200

Question 53

The average permeability is measured where the ______ point is first established.

Answer 53

saturation or knee

Question 54

The point on a magnetization curve where an increase in the applied magnetic field 𝐻 results in little to no increase in magnetization 𝑀. It's where the material is "saturated" with magnetic flux.

Answer 54

saturation or knee point

Question 55

for certain magnetic material, the ______ the area inside the hysteresis loop, the ______ the hysteresis loss

Answer 55

larger, higher

Question 56

In a magnetic circuit, what loses are caused by reversing current direction thousands of times in a coil?

Answer 56

hysteresis loss

Question 57

why is a two-pole magnetic field set up around a coil

Answer 57

because separate lines of magnetic force link and combine their effects