TEST 2 questions

Question 1

The average distance atoms with diffusion coefficient D will diffuse in time t at temperature T is
proportional to,
(A) Dt
(B) DT
(C) (Dt)1/2
(D) (DT)

Answer 1

A

Question 2

(2) Interatomic spacing in materials cannot be characterized by,
(A) Electrons
(B) X-rays
(C) Proximal probes
(D) Laser light

Answer 2

D; wavelength of laser light is too big

Question 3

The visible light reflected or re emitted by a non medtal depends upon

Answer 3

impurities

Question 4

LEDs are based upon:

Answer 4

forward biased p-n junction

Question 5

Which of the following cannot be determined from a tensile stress strain experiment on a metal?
fracture strain
yield strength
dislocation density
toughness

Answer 5

dislocation density

Question 6

how can you characterize ductility

Answer 6

plastic strain at failure

Question 7

Which is the prefereed dislocation slip system in an FCC metal

Answer 7

{111}<110>

Question 8

a polymer can better resist mechanical deformation by

Answer 8

stronger crosslinking