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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Carbon , silicon and germanium have four valence elcectrons each . These are characterised by valence and conduction bands separated by energy band - gap respectively equal to ` (E_g)_(c) (E_g)_(si) ` and ` (E_g)_(Ge) `. Which of the following statements ture ?A. `(E_(g))_(Si) lt(E_(g))_(Ge)lt(E_(g))_(C)`B. `(E_(g))_(C)lt(E_(g))_(Ge)gt(E_(g))_(Si) `C. `(E_(g))_(C)gt(E_(g))_(Si)gt(E_(g))_(Ge) `D. `(E_(g))_(C)=(E_(g))_(Si)=(E_(g))_(Ge) ` |
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Answer» The correct statement is (c). Of the three given elements, the energy band gap of carbon is the maximum and that of germanium is the least. The energy band gap of these elements are related as: `(E_(q))_(C) gt (E_(q))_(Si) gt (E_(q))_(Ge)` |
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| 2. |
Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to `( E _(g))_(c ) , ( E_(g))_(Si ) ` and `( E_(g ))_(G e ) ` .Which of the following statements is true ? (a) `(E_(g))_(Si) lt ( E_(g))_(Ge ) lt ( E_(g))_(C ) ` (b) `( E_(g))_(C ) lt ( E_(g))_(Ge ) gt (E_(g))_(Si)` (c ) `(E_(g))_(C ) gt ( E_(g))_(SI) gt ( E_(g))_(Ge ) ` (d) `( E_(g))_(C ) = ( E_(g))_(Si) = ( E_(g))_(Ge ) ` |
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Answer» Correct Answer - c The energy band-gap is largest for carbon, less for silicon and least for Germanium. |
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| 3. |
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 eVA. 226 nmB. 312 nmC. 432 nmD. 550 nm |
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Answer» Correct Answer - A Energy gap, `E_g=(hc)/lambda, lambda=(hc)/E_g` Here energy gap=5.50 eV Take hc=1240 eV nm `therefore lambda=(1240 eV nm) /(5.5 eV)=226 nm` |
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| 4. |
Assertion : In a semiconductor, the conduction electrons have a higher mobility than holes. Reason: The electrons experience fewer collisions.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 falseD. If both assertion and reason are false. |
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Answer» Correct Answer - C Electrons experience much collisions. The mobility of electrons is more because they require less energy to move, not because they are lighter. |
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| 5. |
Assertion: The conductivity of an intrinsic semiconductor depends on its temperature. Reason The conductivity of an intrinsic semiconductor is slightly higher than that of a lightly doped p-type semiconductor.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 falseD. If both assertion and reason are false. |
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Answer» Correct Answer - C The conductivity of an intrinsic semiconductor is less than that of a lightly doped p-type semiconductor. |
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| 6. |
Assertion: The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature decrease exponentially with increasing band gap. Reason: It will be more difficult for the electron to cross over the large band gap while going from valence band to conduction band.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 falseD. If both assertion and reason are false. |
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Answer» Correct Answer - A To jump from valence band to conduction band electron needs energy equal or more than the forbidden band between these two bands. As the energy of band gap increases, it becomes difficult for electron to get that equivalent energy |
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| 7. |
In a `n`-type semiconductor, which of the following statement is true?A. Electrons are majority carriers and trivalent atoms are the dopants.B. Electrons are minority carriers and pentavalent atoms are the dopants.C. Holes are minority carriers and pentavalent atoms are the dopants.D. Holes are majority carriers and trivalent atoms are the dopants. |
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Answer» The correct statement is (c). In an-type silicon, the electrons are the majority carriers, while the holes are the minority carriers. An n-type semiconductor is obtained when pentavalent atoms, such as phosphorus, are doped in silicon atoms. |
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