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Assertion: If there is some gap between ...

Assertion: If there is some gap between the conduction band and the valence band, electrons in the valence band all remain bound and no free electrons are available in the conduction band. Then the material is an insulator.
Reason: Resistance of insulators is very low

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true not but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false

D

If both assertion and reason are false.

Text Solution

AI Generated Solution

The correct Answer is:
To analyze the given assertion and reason, we will break down the concepts involved step by step. ### Step 1: Understanding the Assertion The assertion states that if there is a gap between the conduction band and the valence band, electrons in the valence band remain bound, and no free electrons are available in the conduction band, then the material is an insulator. **Explanation:** - In semiconductors and insulators, the energy bands are divided into two main categories: the valence band and the conduction band. - The valence band is filled with electrons, while the conduction band is where free electrons can move and conduct electricity. - An insulator has a significant energy gap (band gap) between the valence band and the conduction band. This gap prevents electrons from jumping from the valence band to the conduction band, meaning there are no free electrons available for conduction. ### Step 2: Understanding the Reason The reason states that the resistance of insulators is very low. **Explanation:** - This statement is incorrect. Insulators have very high resistance because they do not have free electrons available to conduct electricity. The lack of free charge carriers leads to high resistance, making it difficult for electric current to flow through the material. ### Step 3: Conclusion Based on the analysis: - The assertion is **true**: The presence of a gap between the conduction and valence bands does mean that the material is an insulator. - The reason is **false**: Insulators have high resistance, not low resistance. ### Final Answer The correct conclusion is that the assertion is true, but the reason is false.
To analyze the given assertion and reason, we will break down the concepts involved step by step. ### Step 1: Understanding the Assertion The assertion states that if there is a gap between the conduction band and the valence band, electrons in the valence band remain bound, and no free electrons are available in the conduction band, then the material is an insulator. **Explanation:** - In semiconductors and insulators, the energy bands are divided into two main categories: the valence band and the conduction band. - The valence band is filled with electrons, while the conduction band is where free electrons can move and conduct electricity. ...
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Knowledge Check

  • Find the wavelength of light that may excite an electron in the valence band of diamond to the conduction band. The energy gap is 5.50 eV

    A
    226 nm
    B
    312 nm
    C
    432 nm
    D
    550 nm

  • Assertion : The electrons in the conduction band have higher energy than those in the valence band of a semiconductor Reason : The conduction band lies above the energy gap and valence band lies below the energy gap.

    A
    If both assertion and reason are true and reason is the correct explanation of assertion.
    B
    If both assertion and reason are true not but reason is not the correct explanation of assertion.
    C
    If assertion is true but reason is false
    D
    If both assertion and reason are false.

  • The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature

    A
    increases exponentially with increasing band gap
    B
    decreases exponentially with increasing band gap
    C
    decreases with increasing temperature.
    D
    is independent of the temperature and band gap.

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