Engineering Materials Objectives Part 02

21 . If a piece of metal is made to have a temperature gradient between its two ends, an
e.m.f is observed to exist between those ends. The above phenomenon is known as
“Thomson effect”.

22 . The atomic radius for simple cubic lattice is “a/2”.

23 . The materials which undergo recoverable deformation and exhibit rubber-like
elasticity are called “Elastomers”.

24 . The materials which exhibit the same elastic properties in all directions are called

25 . Aluminium wire” is expected to be strongest in tension.

26 . Electron” is the heaviest.

27 . Magnesium oxide” MgO is a ceramic material.

28 . Poorest conductor of electricity is “Carbon”.

29 . Bimetallic” type of thermostat is generally used in appliances with heating elements.

30 . Manganin” has zero temperature coefficient of resistance.

31 . Bakelite is “uncombustible”.

32 . Insulating material used in spark plugs is “Porcelain”.

33 . When a loop composed of two dissimilar metals could be made to carry a continuous current simply by maintaining the two junctions at different temperatures, the effect is known as “Seeback effect”.

34 . Thermocouple works on “Seeback effect”.

35 . When a current is passed through the junction of two different metals, heat is absorbed for liberated depending on the direction of the current, the phenomenon is known as “Pltier effect”.

36 . Copper constantan” pairs is commonly used in thermocouples.

37 . The property of materials by which they can be drawn into wires is known as

38 . Dielectric constant for vacuum is “1”.

39 . For most of the solid substances, the value of dielectric constant is “between 1 and 10”.

40 . Electric stress is expressed in terms of “kV/cm”.