30 Questions
Which type of chemical bond is responsible for the properties of metallic materials?
Metallic bond
In intrinsic semiconductors, what is left behind in the valence band when electrons are excited to the conduction band?
Holes
What happens to the number of conduction electrons in Silicon as the temperature increases from 20oC to 50oC?
Increases
Which type of semiconductor conductivity arises from exciting electrons to the conduction band due to a narrow band gap?
Intrinsic conductivity
What determines the width of the energy gap in semiconductors?
Electronegativity difference between elements
Which type of bond strength determines the properties of van der Waals and Hydrogen bonds?
Weakest bond strength
What determines the electrical conductivity in semiconductors?
Charge carrier concentration and carrier mobility
In intrinsic semiconductors, what are the charge carriers?
Both holes and electrons
What is the relationship between electron and hole concentrations in intrinsic semiconductors?
$n_e = n_p$
What is the formula for electrical conductivity in intrinsic semiconductors?
$\sigma = nq(\mu_e + \mu_h)$
What parameter influences the electrical conductivity in semiconductors along with charge carrier concentration?
Temperature
Why are holes considered charge carriers in semiconductors?
Due to their positive charge
What is the FERMI located between?
Acceptor and donor energy level
Which of the following is an example of an acceptor atom?
Ga
What is the formula to calculate the magnitude of polarization in a material?
$zqd$
What causes charge storage in supercapacitors?
Electronic polarization
What does a dipole consist of?
A pair of opposite charges separated by a distance
What does the dielectric constant represent?
Ratio of capacitance with vacuum to dielectric-filled capacitor
What is the fundamental basis for the responses of certain materials to the presence of magnetic fields?
Curie-Weiss Law
Which property is associated with the ability of a material to resist thermal shock?
Expansivity
In the context of electrical properties, what law governs the relationship between voltage and current?
Ohm's Law
Which type of materials exhibit unique behavior at extremely low temperatures by showing zero electrical resistance?
Superconductors
What is the primary focus of optoelectronic mechanism in materials science?
Absorption properties
Which author's work is NOT mentioned as a reference for the course?
Brain S.
What is the formula for conductivity in terms of charge carriers and mobilities?
𝜎 = 𝑛𝑞(𝜇𝑒 + 𝜇ℎ)
At room temperature, how many conducting charges are present per cubic centimeter?
2.51 × 10^13
What type of semiconductors are used for practical applications?
Extrinsic
What is the result of adding a higher valence dopant to a host material?
Extra electron (n-type)
What is the total number of electrons in the valence band at 0 K?
1.77 × 10^23
What is the formula for the number of charge carriers in terms of the number of charge carriers at 0 K and the exponential term?
𝑛 = 𝑛𝑜𝑒x𝑝
Explore the electrical, magnetic, optical, and thermal properties of engineering materials in MSE 255 course at KNUST. Learn about Ohm’s Law, electrical conduction, semiconductors, magnetism, Hysteresis, Optoelectronic mechanism, Curie-Weiss Law, and more.
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