30 Questions
What is the role of free electrons in a conductor?
They are responsible for the conduction of current
Which type of material has a full valence band?
Inert gases
What happens if a substance has an empty conduction band?
It cannot conduct current
What does the forbidden energy gap represent?
The separation between conductance band and valence band
What defines whether the valence band is full or partially filled?
The type of substance
What is the significance of the conduction band being empty in insulators?
Insulators have low conductivity
Which orbit has more energy, the inner or outer orbit?
Outer orbit
What form does an electron emit when it jumps from a higher orbit to a lower one?
Electromagnetic radiations
What is a convenient way to represent the energy of different orbits?
Energy level diagram
In a solid atom influenced by neighboring atoms, do electrons in any orbit have a single energy value?
No, they have a range of energies
What happens to the energy level as the orbit of an electron becomes larger?
The energy level increases
How are the values of radii for orbits determined?
By quantum considerations
Electrons in the third orbit of an atom have _______ energy compared to the electrons in the second orbit.
more
When an electron jumps from a higher orbit to a lower orbit, it _______ energy.
emits
According to Bohr’s theory of atom, which of the following is quantized?
angular momentum of electron
A semiconductor has an almost empty _______ band.
conduction
The electrons in the conduction band are known as _______.
free electrons
In insulators, the energy gap between valence and conduction bands is _______.
very large
According to Bohr, what happens when an electron is given additional energy?
It is lifted to a higher orbit
What is the relationship between the radius of an electron orbit and its energy according to Bohr?
The larger the orbit radius, the greater is the energy
Why does an atom in an excited state not last long?
Because electrons quickly fall back to lower orbits
What happens when an electron falls back to its original lower orbit?
It releases acquired energy as heat, light, or radiation
How many electrons does a silicon atom have according to Bohr's model?
14
What happens if an electron in the first orbit is lifted to the second orbit?
The right amount of energy should be supplied
What happens to the resistance of an insulator as the temperature increases?
Decreases
Why do conductors like copper and aluminium easily allow the passage of electric current?
Due to the overlapping of valence and conduction bands
How can the electrical behavior of conductors be satisfactorily explained?
By the band energy theory of materials
What distinguishes semiconductors from conductors and insulators in terms of energy bands?
Valence band is almost empty, conduction band is almost full
Why is a smaller electric field required in semiconductors compared to insulators to push electrons from the valence band to the conduction band?
Because semiconductors have a small energy gap between bands
What characteristic lies inbetween conductors and insulators that defines semiconductors?
Overlapping energy bands
Test your knowledge about the concepts of valence band and conduction band in atoms. Learn about the energy levels of electrons in the valence band and how it can be completely or partially filled, as well as the behavior of valence electrons in the conduction band of certain materials.
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