Functional Properties And Environmental Interactions Flashcards
Formula for capacitance
C = Q/V or Q = CV
Where Q is the charge on the capacitor, V is the voltage across it, and C is the capacitance (duh)
What are the units of capacitance?
Farads (F)
Which represent Coulombs per Volt (Q/V)
What is capacitance?
The ability of a capacitor to store charge
What are some functional and structural properties?
Functional: optical, electrical, magnetic, thermal
Structural: malleability, hardness, toughness, strength, corrosion resistance
Ductility vs malleability
Ductility is the degree to which a material stretches when put under tensile strengths. This affects the material’s ability to be pulled into a wire
Malleability is a material’s ability to deform under pressure/compressive stress. This affects its ability to be squashed and flattened
Important engineering and functional properties of ceramics
Engineering: refractory (heat resistant), hard, brittle, enreactive, strong
Functional: you can look these up for fun
Magnetic, electrical conduction and insulation, dielectric behaviour, low thermal conductivity, tuneable optical absorption and emission, environmentally dependent surface properties
Important engineering and functional properties of polymers d
Engineering: low density, plastic or brittle depending on temperature, low elastic modulus (compliant)
Functional: magnetic, electrical conductivity? Low thermal conductivity, light emission
Important engineering and functional properties of metals
Ductile and malleable, melt at moderate temperatures, reactive easily oxidised
Magnetic behaviour
Electrical and thermal conduction
Perfect conductor and insulator
A perfect conductor is a hypothetical material in which the charge distribution responds instantaneously to stimuli
A perfect insulator is a hypothetical material in which any charge distribution will persist for an infinite length of time
What is the amount of work done (dW) when moving an electric charge Q in an electric field E?
dW = Fds = -qEds
Electric dipole moment
p = qa
P is the electric dipole moment, q is the magnitude of charge of each charge, a is the distance between them
Current density J
J = I/A
J = sigmaE
Sigma is the conductivity of the material
Sigma =1/p
p is rho, the résistivité of the material
Resistance R
R = l/(A*p)
p is rho the resistivity
Magnetic force due to two parallel wires
dF2 = (u0I1I2ds1ds2)/(4pir^2)
u0 = magnetic constant/permeability of a vacuum = 4pi*10^-7 NA^2
Magnetic flux due to a wire
dB1 = (u0I1ds1)/(4pir^2)
Basically remove ds2 and I2
dF2 = ds2I2dB1
Lorentz force
F = Felectro +Fmagnetic =
qE + qvB
Force parallel to E and perpendicular to both v and B
Which way on the voltage gradient do positive charges move
Positive charges move down the electric potential (voltage) gradient
Electric constant (permittivity of vacuum)
Epsilon subscript 0 but it doesn’t look like he squiggly E like strain, it looks like the euro sign (Chegg)
8.85*10^-12 C^2 N^-1 m^-2
Magnetic constant (permeability of free space/vacuum)
uo (mu subscript 0) is 4pi10^-7 NA^2
Macroscopic polarisation of a material P
P = np
n is the number density of dipoles in the material
p is the polarisation of the individual dipoles (dipoles align with the electric field so p goes from the negative to the positive side of the dipole)
P and p are vectors
What are the three types of polarisation?
Induced dipoles (in the atoms)
Permanent dipoles (e.g. H2O molecule)
Ion displacement
Coulomb’s law in a dielectric
Replace the permittivity of free space (€0)with the permittivity of the dielectric (€)
Check chegg
Linear, areakej, and volumetric expansion
deltaL = loalphadeltaT
Or
deltaL/lo = alpha*deltaT
Where alpha (subscript lowercase L) is the linear coefficient of expansion
deltaA/Ao = 2*alpha*deltaT deltaV/Vo = 3*alpha*deltaT
Flux
What does it mean and google the word for “of area”. Linear, of area, volumetric
Motile
Vs mobile
