Advertisements
Advertisements
Question
- Assertion (A): In insulators, the forbidden gap is very large.
- Reason (R): The valence electrons in an atom of an insulator are very tightly bound to the nucleus.
Options
Both Assertion (A) and Reason (R) are true and (R) is the correct explanation of (A).
Both Assertion (A) and Reason (R) are true and (R) is NOT the correct explanation of (A).
Assertion (A) is true and Reason (R) is false.
Assertion (A) is false and Reason (R) is also false.
Advertisements
Solution
Both Assertion (A) and Reason (R) are true and (R) is the correct explanation of (A).
Explanation:
An insulator is a substance with a high band gap or difference in energy between the valence and conduction bands. Because of the large energy difference, electrons find it difficult to travel to the conduction band, where they can flow and generate an electrical current, implying that the electrons are very firmly bound.
APPEARS IN
RELATED QUESTIONS
Draw the necessary energy band diagrams to distinguish between conductors, semiconductors and insulators.
How does the change in temperature affect the behaviour of these materials ? Explain briefly.
An electric field is applied to a semiconductor. Let the number of charge carries be nand the average drift speed by v. If the temperature is increased,
When an impurity is doped into an intrinsic semiconductor, the conductivity of the semiconductor
In a pure semiconductor, the number of conduction election 6 × 1019 per cubic metre. How many holes are there in a sample of size 1 cm × 1 mm?
The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.
The conductivity of a pure semiconductor is roughly proportional to T3/2 e−ΔE/2kT where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 K?
What is forbidden band?
The valance of an impurity added to germanium crystal in order to convert it into p-type semiconductor is
The reaction between α and β parameter of a transistor is given by
With reference to semiconductor physics, answer the following question.
What is meant by “Forbidden band" of energy levels?
