Question

1.Which of the following statements for Kıc is incorrect?
a) It depends on specimen thickness.
b) In this condition, specimen thickness is much greater than the crack dimensions
c) Kıc is valid in case of plain strain condition
d) Kıc values are relatively large for ductile materials.
e) The magnitude of Kıc diminishes with increasing strain rate.

2. Which of the following statements is correct?
a) A current produced by the net movements of charged ions is called the metallic conduction.
b) The electrical resistivity is directly proportional to specimen geometry.
c) The electrical resistivity for the material is a function of temperature.
d) The energy in the highest filled state at 0°C is called the Fermi energy.
e) All of the above is incorrect.

3. Which kind of conductivity occurs when a bismuth (Bi) atom is added as a substitutional impurity
to germanium (Ge)?
a) Intrinsic semiconductivity
b) n-type intrinsic semiconductivity
c) n-type extrinsic semiconductivity
d) p-type intrinsic semiconductivity
e) p-type extrinsic semiconductivity

4. Which of the following statements is correct?
a) The carrier concentrations increase with temperature for intrinsic and extrinsic semiconductors
b) The magnitude of hole mobility is always greater compared to the electron mobilities.
c) When a high-purity germanium is added 1023 m-3 antimony atoms, antimony will act as an
acceptor in silicon.
d) The hole effect experiment is carried out in order to determine majority charge carrier type,
concentration, and mobility of some material.
e) All of the above is incorrect.

5. Calculate the density of silver at 420°C, given that its room-temperature (25°C) density is 10.49
g/cm3. Assume that the volume coefficient of thermal expansion, αv, is equal to 2αl.
a) 10.49 g/cm3
b) 10.25 g/cm3
c) 10.54 g/cm3
d) 10.33 g/cm3
e) 10.39 g/cm3

6. I) The thermal conductivity of a plain carbon steel is smaller than for a stainless steel.
II) A single quantum of vibrational energy is called a photon.
III) Metals are typically better thermal conductors than are ceramic materials.
IV) Thermal conductivities are higher for crystalline than noncrystalline ceramics.
Which of the above statement(s) are correct?
a) I, III, IV
b) All of them
c) I, II, III
d) III, IV
e) II, III, IV

8. I) There is a coupling interaction between magnetic moments of adjacent atoms/cations for both
material types.
II) Both ferromagnets and ferrimagnets form domains.
III) Saturation magnetizations are higher for ferrimagnetic materials.
IV) Magnetic moment coupling is antiparallel for ferromagnetic materials, and parallel for
ferrimagnetic.
V) Hysteresis B-H behavior is displayed for only ferromagnetic materials, thus permanent
magnetization are possible for ferromagnets.
For ferromagnetic and ferromagnetic materials, which of the above statement(s) are correct?
a) I, II
b) III, IV
c) I, II, III, IV
d) II, III, IV, V
e) I, II, V

9. The nonreflected light fraction which is transmitted through a 125 mm thickness of glass is 0.89.
So, what is the absorption coefficient of this material?
a) 4.12x10-4 mm-1
b) 9.32x10-4 mm-1
c) 1.61x10-4 mm-1
d) 5.82x10-4 mm-1
e) 1.01x10-4 mm-1

10. Indicate whether the following statements are true (T) or false (F)
I) ……The characteristic color of a metal is determined by the distribution of wavelengths of the
absorbed light radiation.
II) ……The characteristic color of a transparent nonmetal is determined by the distribution of
wavelengths of the nonabsorbed light radiation that is reflected from the material.
III) ……Phonons are elastic waves existing within solid materials.
IV)…… The elemental semiconductor germanium is transparent and colorless to visible light.

11. What effect does temperature rise have on semiconductors, why is it different from conductors?
Explain in detail.

12. The quantum mechanics states that there is not any interaction between an accelerating electron
and atoms in a perfect crystal. So all of the free electrons should accelerate as long as the electric
field is applied, which would cause an electric current that is continuously increasing with time.
But as you know, a current reaches a constant value. Explain why.

Answer 1