Electricity And Magnetism Flashcards
1
Q
Cannot be reduced
A
Element
2
Q
Chemically combined
A
Compound
3
Q
Smallest particle
Consist of proton and neutron
A
Atom
4
Q
Mass of proton over electron
A
1836
5
Q
Atomic number of an electron is determined by
A
Number of protons
6
Q
Formula for atomic weight
A
proton + # neutrons
7
Q
Formula for number of electrons in a shell
A
Ne = 2n²
8
Q
Inner to outer
7 shells per atom
A
Orbit / shell
9
Q
Atom loses, gain electrons
A
Ionization
10
Q
electrons removed from valence
A
Free electron
11
Q
Energy gap of a semicon is in the order of
A
One electron volt
12
Q
Classification of materials
A
Conductor
Instulator
Semiconductor
13
Q
Energy gap in the order of 0V
A
Conductor
14
Q
Energy gap in the order of 5eV
A
Insulator
15
Q
In between insulator and conductor
Energy gap in 1eV
A
Semiconductor
16
Q
Energy gap of silicon
A
1.1eV
17
Q
Energy gap of germanium
A
0.67eV
18
Q
Good material conductor have __ valence electron
A
1
19
Q
Presence of electric charge
A
Electricity
20
Q
Electricus
A
Amber
21
Q
Flow of field length
A
Positive to negative
22
Q
Electron flow
A
Negative to positive
23
Q
Hole flow (conventional)
A
Positive to negative
24
Q
Charged body at rest
Attraction or repulsion
A
Electrostatics
25
Unlike charges attract, like repel
1st law of electrostatics
26
2nd law of electrostatics
Coulombs law
27
Size of force is directly proportional to the value of charge
Coulombs law
28
Varies inversely as the square of distance
Coulombs 2nd law
29
Force per unit charge
Space between and around charged bodies
Electric field
30
Electrostatics lines of force are drawn in
Entering negative charge, leaving positive charge
31
Unit of measure of e fielď strength per unit length is known as e field intensity or e intensity
Volt/ meter (V/m)
Joules/ coulomb-meter (J/cm)
Newton/ coulomb (N/c)
32
How does permittivity affect e field intensity
Inversely proportional
It causes field intensity to decrease
33
Easiest way to accumulate static charge
Friction between 2 Insulators
34
Type of contact electrification in which certain material become electrically charged after they come into contact with another diff material through friction
Triboelectric effects
35
Static charge that can be stored by your body as you walk across a carpet
Over 30,000 volts
36
Charged bodies in motion and varying e fields
Electrodynamics
37
Due to ionization of electrons
Random drift
38
Due to potential difference
Directed drift
39
Any directional movement of e charges such as electrons
Electric current
40
Rate of free electrons flow
Current
41
Diff in potential between two paointd that represents the work involved or energy released in the transfer of ____
Potential difference
42
Opposes or limit the flow of current or charge
Resistance
43
Reciprocal of resistance
Conductance
44
Unit of conductance
Siemens or mho
45
Factors affecting resistance
Type of material
Length
Cross-sectional area of material
Temp
46
Does not affect resistance
Mass
47
Resistance of conductor changes with
Temperature
48
The greater the diameter of a wire, the ____ is the resistance
Lesser
49
Ohm's law
I = V/R
50
Best conductor of electricity
Silver
51
Stores electric charge
Capacitance
52
Opposes charge in voltage
Capacitance
53
Stires energy in the form of electrostatic fields
Capacitance
54
Reciprocal of resistance and its unit is ___
Elastance
Daraf
55
Capacitance has a property that opposes
Voltage
56
Simple capacitor
2 copper plates separated by iron (sheet of mica)
57
Voltage required to charge 1.4uF capacitance to 5.6uC
4V
58
Factors that determines the capacitance
Material between plates
Area
Number of plates
Spacing
59
Poor conductor of electricity but efficient supporter of electrostatic field
Dielectric
60
Stores in the form of magnetic field
Inductance
61
Factors affecting inductance
Number of turns
Length
Cross-sectional area of the core
Material
62
Not practical for fabrication in an IC
Inductors
63
Characteristic of inductor
Opposes change in current
64
Attracts pieces of iron
Magnetism
65
Outside of magnet
North to south
66
Inside of magnet
South to north
67
Analogous to voltage
Magnetomotive force (mmf)
68
Magnetic potential
mmf
69
Units of mmf
SI = ampere-turns (AT)
CGS = Gilberts (Gb)
1 AT = 0.4 Gb = 1.26 Gb
70
Magnetic field length, magnetizing force
Magnetic field intensity (H)
71
Units of magnetic field intensity
SI = At/m
CGS = Oersted, Oe = Gb/cm
1 At/m = 0.0126Oe
72
Total number of magnetic lines leaving or entering the pole of magnet
Magnetic flux
73
Analogous to current
Magnetic flux
74
Units of magnetic flux
SI = weber
CGS = Maxwell or lines
1 weber = 1×10⁸ Maxwell
75
Nymber of m field lines per unit area of a SECTION perpendicular to the directionof flux
Flux density
76
Counterpart of flux density
Current density
77
Units of flux density
SI = Teska from Wb/m²
CGS = Gauss from Maxwell/cm²
1 Tesla = 1×10⁴ Gauss = Tesla = Wb/m²
78
The lagging effect between the flux density of the material and the magnetizing force producing it
Hysteresis
79
Ability of a ferro material to withstand an external m field without becoming demagnetized
Coercivity
80
Value of magnetization of a magnetic substance that remain within it even after the applied m field
Rententivity/ Remanence
81
Ability of material to allow m flux to flow through it
Permeability
82
If the flux density for a given mmf is half that of the magnetic field strength, what happens to the absolute permeability
Remains the same
83
Opposition to m flux
Reluctance
84
Analogous to resistance
Reluctance
85
Reciprocal of reluctance is ____ which is analogous to conductance
Permeance
86
Can be magnetized by placing in a strong external magnetic field or by passing electrical current through the material
Ferromagnetic
87
Slightly attracted by a magnetic field and do not retain the magnetic properties when the external field is removed
Paramagnetic
88
Non-metals that exhibit magnetic properties
Ferrimagnetic
89
Magnetic force due to current
Electromagnetism
90
When a current carrying conductor is brohght into magnetic field, the force that moves the conductor depends upon ___
The value of current
91
Law when an induced emf is set up whenever the magnetic field linking that circuit changes
Faradays's first law
92
Law when the magnitude of the induced emf in any circuit is propotional to the rate of change of the magnetic flux linking the circuit
Faraday's second law
93
The direction of an induced emf is always such that it tends to set up a current opposing the moyion or the change of flux responsible for inducing that emf
Lenz' law
94
When a conductor is moved across a magnetic field so as to cut through the lines of force (or flux),an emf is produced in the conductor
Electromagnetic induction
