MSE 2001 Exam 1 Terms - Electrical/Magnetic/Optical

Maximum Service Temperature

maximum “useable” temperature for a material.

How might heated material fail?

melt, sag, break, corrode, decompose

Heat Capacity

the energy required to raise the temperature of a material by 1K

Thermal Conductivity

the rate at which heat flows through a material given a known temperature gradient

What law is this?

Fourier’s Law

Fourier’s Law

the rate of heat transfer through a material is proportional to the negative temp gradient and the area perp to the heat flow.

What materials are most conductive?

pure metals

What materials are least conductive?

gases

Thermal Diffusivity

an estimate of how quickly a material will heat up when a heat source is applied; describes transient heat flow

What equation is this?

Thermal diffusivity

What does this formula represent?

Thermal Expansion

Thermal Expansion Coefficient (a)

change in volume of a material with change in temperature

Electrical Conductivity

how quickly electrons travel through the materials

Electrical Resistivity

the impediment to electron flow

What performance parameter does this equation represent?

electrical resistance

What is a Dielectric?

an electrical insulator

What is an electrode?

an electrical conductor

What is the function of a capacitor?

store electrical energy by separating charge

What does this design equation represent?

capacitance

What does this ε term represent?

permittivity of free space

What does k represent?

dielectric constant

What are the two important material properties for a Capacitor?

dielectric constant and resistivity

Dielectric Constant

how much charge can be stored

Capacitor Resistivity

how long you can store energy without the capacitor discharging

Piezoelectricity

a cross-property combining both the electrical and mechanical response of a material.

Piezoelectrics

electrical insulators that support an internal applied voltage to function

Piezoelectric Effect

applying a mechanical strain to get a voltage

Electrostriction

applying a voltage and get a mechanical strain

What does this equation represent?

Magnetization

Magnetization (M)

the material’s response to an applied magnetic field (H)

Magnetic Susceptibility (X)

a property of a material that is a mathematical function of the magnetic field (H)

What are some examples of magnetic materials?

ferromagnets and ferrimagnets

What are examples of non-magnetic materials?

paramagnets, diamagnets, antiferromagnets

Soft Magnetic Materials

magnetize when applied to a magnetic field and demagnetize when removed.

Hard Magnetic Materials

magnetize when applied and removed from a magnetic field.

What material does this plot represent?

Hard Magnets

What is does the green line represent on this plot?

remanent magnetization

What does the yellow line represent on this plot?

saturation magnetization

What material does this plot represent?

soft magnets

Saturation Magnetization

maximum magnetization that a material can obtain when placed under a magnetic field

Remanence (Remanent Magnetization)

how much magnetization remains after you remove the magnetic field

Coercive Field

temperature above which a permanently magnetized material looses its magnetization

Curie Temperature

temperature above which a permanently magnetized material loses its magnetization.

What can happen to the light when it is incident on a material?

transmitted, reflected, or absorbed

Reflectivity

% incident light that is reflected by the material’s surface

Absorptivity

% of incident of light that is absorbed by the material

Transmissivity

% of incident of light that is transmitted through the material and exits on the other side

What do reflectivity, absorptivity, and transmissivity depend on?

wavelength of incident light and the angle of incidence

Introducing roughness on surface so that the incoming light can?

increase reflection

Polarization of Light

light consists of an electric and a magnetic field oscillating perpendicular to one another

Polarization Direction

direction in which the electric field is oscillating

Light is linearly polarized in what direction?

z-direction

Randomly Polarized Light

light waves with electric fields in all directions

Polarizer

a material that can make light linear polarized when passing through

Refractive Index

the ratio of the velocity of light in a vacuum to the velocity of light traveling in a material.