Chapter 4

Question 1

Define: Density

Answer 1

Weight per unit Volume

Question 2

Define: Specific Gravity

Answer 2

Density of a material relative to the density of water and is therefore a ratio with no units

Question 3

Define: Thermal Expansion

Answer 3

Measures the change in length per degree of temperature. Length ratio.

Question 4

Define: Melting Point

Answer 4

Temperature at which the material transforms from a solid to liquid state

Question 5

Define: Freezing Point

Answer 5

Temperature at which the material transforms from a liquid to solid state

Question 6

Define: Heat of Fusion

Answer 6

Amount of heat energy need to accomplish phase changes from solid to liquid and vice versa.

Question 7

Define: Supercooled Liquid

Answer 7

When an element remains a liquid even at temperatures below its freezing point; due to nucleation of crystals not initiating immediately

Question 8

Define: Solidus

Answer 8

In metal alloys, melting begins at a certain temperature (solidus), which continues to rise as full transition from solid to liquid occurs

Question 9

Define: Liquidus

Answer 9

In metal alloys, when all material is in the liquid state, the temperature is referred to as (liquidus)

Question 10

Define: Specific Heat

Answer 10

Quantity of heat energy required to increase the temperature of a unit mass of the material by one degree. (C: J/kg-K)

Question 11

Define: Thermal Conductivity

Answer 11

“k”: J/s-mm-K ; the capacity of a substance to transfer heat through itself by physicial mechanism

Question 12

Define: Resistivity

Answer 12

Basic electrical property that defines a material’s capability to resist current flow; “r”.

Question 13

Define: Conductivity

Answer 13

Basic electrical property that defines a material’s capability to conduct current flow; “c”.

c = 1/r

Question 14

Define: Conductors

Answer 14

Metals with low resistivity.

Question 15

Define: Insulators

Answer 15

Materials with high resistivities

Question 16

Define: Dielectric

Answer 16

Term given to insulators to mean a “nonconductor of direct current”. However, if the voltage is high enough, current will form an arc and pass.

Question 17

Define: Superconductor

Answer 17

Exhibits zero resistivity and observed in certain materials at low temperatures approaching absolute “0”.

Question 18

Define: Semiconductor

Answer 18

Material whose resistivity lies between insulators and conductors; commonly used element: silicon. Useful in fabricating integrated circuits.

Question 19

Define: Electrolyte

Answer 19

An ionized solution in which electrolytic conduction requires that current enter and leave the solution at electrodes (anode and cathode)