MSE2001 Exam 4 V11
10 Volts is applied on a wire with a length of 2 meters, and this results in a current of 100 Ampere. The electric field (E) in the wire is _______. A. 5 Volts/meter B. 10 Volts/meter C. 1.0 Volts/meter D. None of the above
A
As temperature increases, the mean time between collisions of electrons in a conductor A. Reduces B. Increases C. Stays the same
A
As temperature increases, which one of the following statements is INCORRECT? A. The energy of an energy band increases B. The charge mobility decreases C. The drift velocity of electrons decreases D. As the temperature increases, the probability of an electron to occupy higher energy levels is increased.
A
Based on the Fermi-Dirac distribution fraction: f(E) = 1/(exp(E-Ef)/kT) +1), which one of the following statement is correct? A. At E < Ef, f(E) = 1 at 0 K B. At E = Ef, f(E) = 1 at any temperature C. At E > Ef, f(E) = 1 at 0 K D. None of the above
A
Based on the Fermi-Dirac distribution function, which one of the following statement is correct? A. At E < Ef, f(E) = 1 at 0 K B. At E = Ef, f(E) = 1 at any temperature C. At E > Ef, f(E) = 1 at 0 K D. None of the above
A
Equation Ne = N0exp(−Eg/2kT) applies to _______ A. A material with a band gap B. A material with no band gap C. Both A and B D. Neither A or B
A
In Maxwell model, elastic spring and viscous dashpot are connected in _____. A. Series B. Parallels C. Both series and parallels D. None of the Above
A
In a solid, which energy band has the highest energy? A. The conduction band B. The forbidden band C. The valence Band D. The core band
A
In the Maxwell model, which element dissipates energy? A. Dashpot. B. Spring. C. Both spring and dashpot can dissipate energy. D. None of above is correct.
A
The mean time between collisions of electrons in a conductor will be ______by lattice defects. Thus the mobility of electrons will be _______. A. Decreased, decreased B. Increased, increased C. Decreased, increased D. Increased, decreased
A
Toughness in tensile test is defined as _______________. A. The area underneath the stress-strain curve B. The highest stress C. The maximum elongational strain D. The fully recoverable strain
A
Which of the following is NOT the correct unit of electrical conductivity? A. Ω-(cm-1) B. (Ω-m)-1 C. (Ω-cm)-1 D. Siemens per meter
A
Which one of the following figures is likely to represent the stress-strain curve of a metal? A B C D
A
Which one of the following has the highest electrical conductivity? A. Silicon (Si) B. Polyethylene C. Polystyrene D. Polypropylene E. Nylon F. All of them have comparable electrical conductivity
A
Which one of the following will not lead to plastic deformation? A. Bond stretching B. Dislocation movement C. Sliding of entangled long-chain molecules D. None of the above
A
Which point represents the limit of linear elastic strain? A. Point A B. Point B C. Point C D. None of the above
A
Which strain represents the permanent plastic deformation? A. OC B. CD C. OD D. None of the above
A
Which strain represents the permanent plastic deformation? A. OC B. CD C. OD D. None of the above
A.
Which one of the following is the initial modulus? A. 1 GPa B. 10 MPa C. 100 MPa D. None of the above E. Modulus can not be determined from the stress-strain curve.
A. 1 GPa
A solid characterized by a partially filled valence band is a(n) _____. A. Conductor B. Semiconductor C. Insulator
A. Conductor
A hypothetical material with a Poisson ratio of -0.1 will _________ in lateral dimensions when being under uniaxial tension. A. Expand B. Shrink
A. Expand
Which material has the lowest ductility? A. Material Ⅰ B. Material Ⅱ C. Material Ⅲ
A. Material Ⅰ
For a band gap material, number of electrons in the conduction band at a given temperature is given by which of the following equation? (symbols have their usual meaning) A. Ne = N0 exp(− Eg / 2kT) B. Ne = N0 exp(Eg / 2kT) C. Ne = N0 exp(−Eg^2 / 2kT) D. none of the above
A. Ne = N0 exp(− Eg / 2kT)
As temperature increases, which one of the following statements is INCORRECT? A. The energy of an energy band increases B. The charge mobility decreases C. The drift velocity of electrons decreases D. As the temperature increases, the probability of an electron to occupy higher energy levels is increased.
A. The energy of an energy band increases
Creep behavior is measured at _________. A. Constant strain B. Constant stress
B
For isotropic material, relationship between tensile modulus and shear modulus is given by which of the following equation? A. G = E/3(1-2v) B. G = E/2(1+v) C. G = 2E/(1+v) D. None of the above
B
For isotropic material, the relationship between Young's modulus and shear modulus is given by A. G = E/3(1-2v) B. G = E/2(1+v) C. G = 2E/(1+v) D. None of the above
B
In which test is the strain maintained constant? A. Creep test B. Stress relaxation test
B
Definition of stress is ________? A. Force x cross-sectional area B. Force/cross-sectional area C. Force/change in length D. Force x change in length
B. Force/cross-sectional area
Which region represents the recoverable work? A. Region 1 B. Region 2 C. Region 1 + Region 2 D. None of the above
B. Region 2
Which of the following conductivity equation is correct for NaCl, assuming that charge is transferred by motion of ions only? (All symbols have their usual meaning) A. σ = qe ( NNa * μNa + 2 NCl * μCl ) B. σ = qe ( NNa * μNa + NCl * μCl ) C. σ = qe ( 2 NNa * μNa + NCl * μCl ) D. none of the above
B. σ = qe ( NNa * μNa + NCl * μCl )
A band gap material with a large band gap is likely to be a(n) _________________. A. Conductor B. Semiconductor C. Insulator
C
According to Hooke's law, which of the following is correct? (Symbols have their usual meaning) A. B. C. D. none of the above
C
Rubber typically has a Poisson ration close to ____? A. 0 B. 0.3 C. 0.5 D. 1
C
The number of mobile electrons per atom for aluminum (Z = 13) is ______________. A. 1 B. 2 C. 3 D. 4
C
Which material is not a band gap material? A. Silicon B. Diamond C. Copper D. Aluminum doped silicon
C
Which of the following is an example of a very high modulus material? A. Plexiglass (PMMA) B. Al2O3 C. Diamond D. Stainless steel
C
Which one of the following equation is applicable to an elastic material? A. o=n*de/dt B. o=Ee C. o(t)=o0exp(-t/r0) D. none of the above
C
Which one of the following is the strain to failure? A. 1% B. 2 % C. 6% D. None of the above
C
Based on the following energy band diagrams, which one of the following statements is incorrect? A. Diagram a represents conductor B. Diagram b represents semiconductor C. Diagram c represents semiconductor D. Diagram c represents insulator
C.
A material has yield strength of 350 MPa and elastic modulus of 70 GPa. What is the yield strain for this material? Assume that deformation up to the yield point is linear elastic. A. 1.0 % B. 0.1 % C. 0.5 % D. 5.0 % E. None of these
C. 0.5 %
The critical energy gap to distinguish between a semiconductor and an insulator is approximately _________________. A. 1.0 eV B. 0.1 eV C. 2.5 eV D. 0.25 eV
C. 2.5 eV
Definition of strain is ________? A. Original length/change in length B. Original length x change in length C. Change in length/ original length D. None of the above
C. Change in length/ original length
For an incompressible material, the elastic bulk modulus is equal to ____________. A. 0 B. 1 C. Infinity D. None of the above
C. Infinity
Which material has the lowest modulus? A. Material I B. Material II C. Material III
C. Material III
Which of the following is the correct unit of electrical conductivity? A. Ampere B. Ohms per meter C. Siemens per meter D. None of the above
C. Siemens per meter
Based on the following electron distribution in Figures A and B, which one of the following statements is correct? A. The number of charge carriers in Figure A is greater than in Figure B B. The number of charge carriers in Figure A is less than in Figure B C. The number of charge carriers in Figure A is same as in Figure B D. None of the above
C. The number of charge carriers in Figure A is same as in Figure B
Assuming linear relationship between voltage and current, what voltage will be required to produce a current of 5 Ampere in a wire with a resistance of 0.1 Ω? A. 5 Volts B. 500 Volts C. 50 Volts D. None of the above
D
For electrical conduction, which of the following is NOT correct? (symbols have their usual meaning) A. V = IR B. p = A/L R C. sigma = 1/p D. q = N*sigma*u E. All of the above
D
For electrical conduction, which of the following is correct? (symbols have their usual meaning) A. V = IR B. p = A/L * R C. sigma = 1/p D. sigma = Nqu E. All of the above
D
Which material property has a unit different from the other three? A. Young's Modulus B. Tensile Strength C. Yield Stress D. Poisson Ratio
D
Which of the following has the highest electrical conductivity? A. Polyethylene B. Window glass C. P (phosphorus) doped Si D. Silver
D
Which of the following has the highest electrical conductivity? A. Polyethylene B. Window glass C. P doped Si D. Silver
D
Which one of the following has the lowest electrical conductivity? A. Polyethylene B. Nylon C. P (phosphorus) doped Si D. Teflon or poly(tetra fluoroethylene) or PTFE
D
which one of the following equation is the correct equation of the conductivity of a semi conductor as a function of temperature A) omega = omega0 exp(-Eg/kT) B) omega = omega0 exp(Eg/kT) C) omega = omega0 exp(Eg/kT)^2 D) none of the above
D
Which one of the following is the initial modulus? A. 100 MPa B. 150 MPa C. 200 MPa D. 20 GPa E. None of the above
D. 20 GPa
Which one of the following is the strain to failure? A. 2 % B. 3 % C. 4 % D. None of the above
D. None of the above
Which one of the following solids has the highest electrical conductivity? A. Aluminum B. Copper C. Gold D. Silver
D. Silver
Which of the following is an example of high modulus material? A. Plexiglass (PMMA) B. Polypropylene C. Polystyrene D. Stainless steel.
D. Stainless steel.
On a tensile stress-strain curve, which value is the highest? A. Stress at the elastic limit B. Stress at the yield point C. Stress at fracture D. Tensile strength
D. Tensile strength
When stress is applied on a metal rod with a length of 40 mm and diameter of 10 mm, the length and diameter of the deformed rod are 40.0168 mm and 9.9986 mm. This value of Poisson's ratio of this metal is _________. A. 0.4 B. 0.25 C. 0.2 D. 0.33 E. None of these
D.0.33
Modulus of a thermoplastic polymer _____ with increasing temperature. This behavior is particularly dominant above glass transition temperature. A. Decreases B. Increases C. Does not change
Decreases
Modulus can be measured in which of the following modes? A. Tension B. Compression C. Torsion D. Bending E. Shear F. All of the above
F
Addition of 2 phosphorus atoms in 1 million copper atoms will increase the electrical conductivity of copper significantly. This statement is _____? True False
False
Carbon in the form of graphite is an electrical insulator. This statement is _______. True False
False
Griffith equation is applicable to a ductile materials. This statement is _______? True False
False
In Griffith equation, a is two times the crack length. This statement is ____. True False
False
In all materials, resistivity decreases with increasing temperature. This statement is ____. True False
False
In most materials, resistivity increases with increase in temperature. True False
False
Modulus of a thermoplastic polymer does not change with increasing temperature. This statement is ______. True False
False
The elongation to break increases as the deformation break increases in silly putty, this statement is True False
False
The elongation to break increases as the deformation rate increases in silly putty. This statement is (True/False)?
False
Viscoelastic deformation is fully recoverable. This statement is ____? True False
False
Aligned thermoplastics exhibit _____ modulus in the direction of alignment than unoriented thermoplastic polymer. Higher Lower
Higher
A hypothetical material with a Poisson ratio of -0.1 will expand in lateral dimensions when being under uniaxial tension. This statement is ______. True False
True
A material with Poisson's ratio of zero, has zero strain in the lateral (perpendicular or horizontal) direction when stretched along the axial (or vertical) direction. True False
True
A material with an energy band gap of 5 eV will be an insulator. This statement is ______. True False
True
Addition of B (boron) to Si is an example of p-type of conductor. This statement is _____. True False
True
Addition of Boron to Si creates a p-type of semi-conductor. This statement is ______. True False
True
Addition of P to Si creates n-type of conductor. This statement is ______________. True False
True
Addition of two P (phosphorus) atoms to 1 million Si (silicon) atoms increases the conductivity by a factor of 5 million. This statement is _____. True False
True
Band gap of a semiconducting material can be determined by measuring its conductivity as a function of temperature. This statement is _______. True False
True
Both electrons and holes can transport charge. This statement is _____. True False
True
Carbon in the form of diamond is an electrical insulator. This statement is _______. True False
True
Carbon in the form of graphite is an electrical conductor. This statement is _____. True False
True
Carbon in the form of graphite is an electrical conductor. This statement is ____. A. True B. False
True
Diamond is an example of a very high modulus material. This statement is ______. True False
True
Elastic deformation is fully recoverable. This statement is ____? True False
True
For most materials, the true stress is higher than the engineering stress. This statement is _____. True False
True
Griffith equation is only applicable for brittle materials and not for ductile materials. This statement is _______. True False
True
Griffith theory predicts that theoretical strength of a material is about 10 % of its Young's modulus. This statement is ______. True False
True
In superconducting materials, resistivity approaches zero. This statement is ____. True False
True
Metal oxides, many ceramics, and most polymers are electrical insulators Ture False
True
Modulus of BCC iron along <111> is ~ 280 GPa, while along <100> is ~ 125 GPa. The modulus of polycrystalline iron is ~ 200 GPa. These statements are______? True False
True
Most common semiconductor materials such Si and Ge have covalent bonds. This statement is ________. True False
True
Phosphorus doped Si has higher electrical conductivity then pure Si. True False
True
Some polymers are electrical conductors. Polyaniline is an example of electrically conducting polymer. True False
True
Thermoelectric effect can be used to measure the temperature. This statement is _______. True False
True
Which one of the following figures represents the stress-strain curve of a ceramic material? figure (a) figure (b) figure (c) figure (d)
figure (d)
which one of the following has the lowest electical conductivity
nylon