ChE 361 #4

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What is the SI unit of current?

ampere(A)
What is the SI unit of resistance?

ohm
What is the SI unit of resistivity?

ohm*meter
What is the SI unit of conductance?

siemens(S)
What is the SI unit of conductivity?

siemens per meter(S/m)
What is the SI unit of electrical potential?

volt(V)
Who is credited with the idea of positive and negative charges?

Ben Franklin
V=?

J/C
How do solutes affect the yield strength of a metal?

Increase yield
How do solutes affect the resistivity of a metal?

Increase resistivity
How does temperature affect the yield strength of a metal?

As T increases yield decreases
How does temperature affect the resistivity of a metal?

As T increases resistivity increases
According to the text, what is true of ionic solids?

Ionic solids conduct at temperatures high enough to promote rapid ionic diffusion
What is n_v in the equation k_e=n_ve(mu_e)?

Number density of free electrons
What is mu_e in the equation k_e=n_v(mu_e)?

Mobility of fee electrons
What is true of ionic bonds?

Valence electrons are tightly held by anions
What is true of covalent bonds?

Valence electrons are localized in bonding orbitals
What is true of metallic bonds?

Valence electrons are delocalized
What is true of secondary bonds?

Dipoles interact
What contributes to good electrical conductivity?

Valence electrons are delocalized
What contributes to good thermal conductivity?

Valence electrons are delocalized
What are valence electrons?

Electrons in outermost occupied shell
How do defects affect the charge carriers in a metallic conductor?

Defects scatter charge carriers
Which materials may retain polarization in the absence of an external electric field?

Ferroelectrics
Which materials change shape appreciably when polarized?

Conductors
Which materials ave little or no electrical resistance at very low temperatures?

Superconductors
Which materials become polarized when strained?

Piezoelectrics
Which materials are typically used to insulate electrical wires and cables?

Dielectrics
Which materials become polarized when heated?

Conductors
What is meant by the capacitance of a material?

Ability to conduct electrons
What happens at the breakdown voltage?

Significant current occurs in an insulator
What is the term for two charges +q separated by a small distance delta(x)?

Dipole

Author

deshayes

53048

Card Set

ChE 361 #4

Description

Engineering materials final

Updated

2010-12-03T06:59:50Z

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