Electrical Engineering Materials

Question 1

Properties that decides material uses

Answer 1

MEMTOD

Question 2

Mechanical properties

Answer 2

deformation by applied pressure showing elastic modulus , strength and toughness

Question 3

Electrical properties

Answer 3

apply electric field showing conductivity, resistivity

Question 4

Magnetic properties

Answer 4

apply magnetic field showing EMF

Question 5

Thermal properties

Answer 5

apply heat energy showing thermal conductivity , heat capacity

Question 6

Optical properties

Answer 6

apply electromagnetic or light radiation showing index of refraction , reflectivity

Question 7

Deteriorative properties

Answer 7

Chemical reactivity of materials

Question 8

To design, production, and utilization of materials, there are four elements to conside

Answer 8

Performance depending on Properties which is function of Structure that is determined by how material is processed. P3S

Question 9

Criteria in materials selection

Answer 9

in-service conditions subjected, deterioration due to operations and economics or cost

Question 10

Generic Classification of Materials

Answer 10

Metals Alloys , Ceramics & Glasses , Organic polymers

Question 11

Examples of Metals & Alloys Material

Answer 11

Steels, aluminum, copper, iron, silver, gold, brass, bronze, super alloys, boron rare earth magnetic alloys

Question 12

Examples of Ceramics & Glasses

Answer 12

MgO, CdS, Al2O2, SiC, BATiO3, Silica, soda-lime glass, concrete, cement, ferrites, ceramic superconductors

Question 13

Examples of Organic polymers

Answer 13

PVC, PTFE, Polyethylene Fibers like nylon, cotton, natural & synthetic rubbers, leather

Question 14

Classification of Materials from Elec.Engg POV

Answer 14

Conductors, Insulators ( dielectrics ) , Magnetic Materials , Semiconductors

Question 15

Conductors ?

Answer 15

difference in electric potential leads to passage of electric current due to free electrons

Question 16

Ohm’s Law

Answer 16

Voltage across a conductor is directly proportional to the current flowing through it, if physical conditions and temperature remain constant.

Question 17

Joule heating

Answer 17

Conversion of electrical energy into heat energy

Question 18

Joule’s Law

Answer 18

Heat produced by an electric current i flowing through a resistance R for a time t is proportional to i 2 Rt.

Question 19

Relationship b/w Elect.conductivity and thermal conductivity

Answer 19

Ratio of the electronic contribution of the thermal conductivity to the electrical conductivity of a metal is proportional to the temperature. Kσ=LT
K is the electrical component of the thermal conductivity, σ is the thermal conductivity, T is the absolute temperature, and L is the Lorentz number.

Question 20

Use of conductors based on their resistivity

Answer 20

Low resistivity - Conductors, High Resistivity - resistors or heating elements , Zero resistivity - Superconductors that operate below critical or transition temperature

Question 21

Insulators ? AM I Dielectric ?

Answer 21

used as insulation b/w 2 media which is at diff.potential and also stores. Insulation- Insulating Materials, if stores elect.charges - Dielectric Materials

Question 22

Magnetic Material

Answer 22

Used to gen elec.power, elec.motors, visual images in scanners, stores info in computers. Pure element Iron, Cobalt, Nickel and godolinium