Electrical and Electronic Circuits

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What is the temperature coefficient equation?
The meaning of each part
R = Rref[ 1 + a(T-Tref)]
R = conductor resistance at temp "T"
Rref = Conductor resistance at temp "Tref"
a (alpha) = Temperature coefficient of resistance for conductor material
T = Conductor temperature in Celsius
Tref = Reference temperature
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How does temperature vs resistance work in NTC and PTC thermistors
PTC = as temp increases so does resistance
NTC = as temp increases, resistance decreases
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What is absolute Permittivity
The absolute permittivity of a dielectric material is the product of permittivity of free space and the relative permittivity of the material
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What is relative Permittivity
Flux density of the field in dielectric / flux density of the field in a vacuum
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What is a dielectric constant
The dialectic constant is the relative permittivity for a substance or material
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Types of dielectric material
(Name minimum of 3)
Polyester PET
Glass
Paper
Air
Tantalum Oxide
Aluminium Oxide
Polypropylene
Ceramic Porcelain
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Why are capacitors rated?
Avoid explosion and injury from higher voltages than intended
May cause capacitor to break down / become defective
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What's the equation for dielectric strength
Voltage / Thickness (V/M)
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Working out variable capacitance?
Y = mx+c
or Rise/Run
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What is the equation for charge?
Q = CV

Q = Charge (Coulombs)
C = Capacitance (farads)
V = Potential difference (Volts)
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What is the Equation for energy stored
W = 1/2 (CV)^2

W = Energy (Joules)
C = Capacitance (farads)
V = Potential difference (Volts)
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The equation for working out magnetomotive force (MMF)
MMF = NI

N = Number of turns
I = Current in the wire

MMF(Amp-Turns / A-T)
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Flux Density formula
Flux Density (B) =
Flux Φ / Area through which flux passes (A)

B = Φ/A
Φ = BA

Measured in Tesla
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Formula for magnetic field strength (H)
H = NI/l

N = Number of turns
I = Current in the wire
l = Length of the substance

OR

H = MMF/L
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Energy Stored in inductor equation
Energy stored = 1/2 LI^2

L = Inductance (henrys - H)
I = the current through the inductor
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Other cards in this set

Card 2

Front

How does temperature vs resistance work in NTC and PTC thermistors

Back

PTC = as temp increases so does resistance
NTC = as temp increases, resistance decreases

Card 3

Front

What is absolute Permittivity

Back

Preview of the front of card 3

Card 4

Front

What is relative Permittivity

Back

Preview of the front of card 4

Card 5

Front

What is a dielectric constant

Back

Preview of the front of card 5
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