Biomaterials Final Exam

Electric current is a measure of [a] _____ passing per unit [b], and the base units of current are [c]____ per [d]____, otherwise known as an [e].

Electric current is a measure of [a] _____ passing per unit [b], and the base units of current are [c]____ per [d]____, otherwise known as an [e].

charge time coloumb second ampere

All electrons present in a material are available to participate in conduction process.

T or F

False

Are energies for holes greater or less than the Fermi energy?

Greater than

Less than

Less than

The electrical conductivity of an intrinsic semiconductor is

a. characteristic of the high-purity metal.

b. due to the presence of impurities.

characteristic of the high-purity metal.

How does increasing temperature affect the concentration of both electrons and holes in an intrinsic semiconductor?

Increases the concentration.

Decreases the concentration.

May increase and/or decrease the concentration, depending on the temperature range.

Increases the concentration.

Which type of charge carrier will be introduced into a semiconductor by the presence of an acceptor impurity?

Electron

Hole

Hole

For an n-type semiconductor, which type of charge carrier is present in the greater concentration?

Electron

Hole

Electron

Which of the following are preferred for semiconducting devices?

Single crystals

Polycrystalline materials

Single crystals

An insulator has an energy band gap that is relatively

a. Wide

b. Narrow

wide

Ferrous alloys are used extensively as engineering materials because of its:

vailability in abundance

cost effectiveness in extraction, refining and fabrication

tailorability to have a wide range of mechanical properties.

all of the above

all of the above

Cast alloys are amenable to forming by deformation.

T or F

False

Refractory ceramics are used as lining for furnaces and smelters due to their capacity to withstand high temperatures without melting, decomposing and remain unreactive in severe environments.

T or F

True

Graphene has the potential to be fabricated into transistors, super capacitors, electrical conductors, and biosensors due to its:

high thermal conductivity

low electrical resistivity

chemical inertness

all of the above

all of the above

Ultra-high-molecular-weight Polyethylene (UHMWPE), despite its enhanced mechanical properties to Polyethylene (PE), deteriorates rapidly at high temperatures due to:

low coefficient of friction

low melting temperature

high impact resistance

all of the above

low melting temperature

Plastic deformations caused during metal forming operations, at temperatures above the point of recrystallization is known as

cold working

hot working

casting

molding

hot working

Alloys with low ductility are fabricated using casting due to the complexity in shaping them with hot or cold working.

True

False

True

Heating materials at high temperatures and gradual cooling, known as annealing, is done to:

reduce strain in the material

increase ductility and toughness of the material

clear rust/corrosions from the material

all of the above

increase ductility and toughness of the material

When glass pieces are cooled, internal thermal stresses may be generated due to the differences in cooling rate between interior and surface regions

True

False

True

Plasticizer occupy space in-between large polymer chains, increasing interchain distance and reducing secondary intermolecular bonding.

True

False

True

On both quizzes

-

On first quiz

-

be able to draw what is inside bottom purple circle

-

-

Which of the following current-voltage plots is consistent with the behavior of a p-n junction?

a

A semi-conductor has an energy band gap that is relatively

a. Wide

b. Narrow

Narrow