SECTION-4

#### ENGINEERING MATERIAL OBJECTIVE QUESTIONS/MCQ

##### Q31. Heat always flows in the direction of a

(a) positive thermal gradient
(b) negative thermal gradient
(c) zero thermal gradient
(d) none of the above.

Ans:  (b) negative thermal gradient

##### Q32. The heat flow through an area A, perpendicular to the direction of flow is

(a) directly proportional to the area
(b) directly proportional to the thermal gradient
(c) both (a) and (b)
(d) none of the above.

Ans:  (c) both (a) and (b)

##### Q33. The presence of pores, impurities, and other defects tends to shorten the mean free path and hence conductivity

(a) increases
(b) decreases
(c) remains constant
(d) none of the above.

Ans:  (a) increases

##### Q34. The quantity of heat that must be added to a unit mass of a solid to raise its temperature by one degree is known as

(a) specific gravity
(b) specific heat
(c) specific energy
(d) none of the above.

Ans:  (c) specific energy

(a) 1
(b) 6
(c) 12
(d) 18.

Ans:  (b) 6

##### Q36. If the atoms always vibrate symmetrically about their equilibrium positions, their average spacing would be constant and the thermal expansion will be

(a) maximum
(b) zero
(c) average
(d) none of the above,

Ans:  (b) zero

##### Q37. The actual energy curve for atoms of a solid is

(a) symmetrical about the vertical line
(b) not symmetrical about the vertical line
(c) symmetrical about a line passing through origin and making an angle 45° with x-axis
(d) none of the above.

Ans:  (b) not symmetrical about the vertical line

##### Q38. In case of actual energy curve, at the energy level increases, the average spacing between the atoms

(a) decreases
(b) increases
(c) remains constant
(d) none of the above.

Ans:  (b) increases

##### q39. The rate of change of length with respect to temperature per unit length is known as

(a) specific heat
(b) co-efficient of thermal expansion
(c) co-efficient of viscosity
(d) co-efficient of friction.

Ans:  (b) co-efficient of thermal expansion

##### Q40. For body-centred cubic crystals, γ is generally various from

(a) 0.5 to 1.0
(b) 1.17 to 1.75
(c) 2.1 to 3.4
(d) 4 to 6.

Ans:  (b) 1.17 to 1.75

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##### Read More Sections of Engineering Materials

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Engineering Material Objective Questions – Section-1

Engineering Material Objective Questions – Section-2

Engineering Material Objective Questions – Section-3

Engineering Material Objective Questions – Section-4