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Q. No.In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is a/an:
| 1. | \(\mathrm{p}\text-\)type semiconductor |
| 2. | insulator |
| 3. | metal |
| 4. | \(\mathrm{n}\text-\)type semiconductor |
Subtopic: Â Energy Band theory |
 74%
From NCERT
AIPMT - 2007
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Identify the incorrect statement from the following:
| 1. | The resistivity of a semiconductor increases with an increase in temperature. |
| 2. | Substances with an energy gap of the order of \(10~\text{eV}\) are insulators. |
| 3. | In conductors, the valence and conduction bands may overlap. |
| 4. | The conductivity of a semiconductor increases with an increase in temperature. |
Subtopic: Â Energy Band theory |
 78%
From NCERT
AIPMT - 2005
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Carbon, Silicon, and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy gaps represented by \(\left(E_g\right)_C,(E_g)_{Si}~\text{and}~(E_g)_{Ge}\) respectively. Which one of the following relationships is true in their case?
| 1. | \(\left(E_g\right)_C<\left(E_g\right)_{G e} \) | 2. | \(\left(E_g\right)_C>\left(E_g\right)_{S i} \) |
| 3. | \(\left(E_g\right)_C=\left(E_g\right)_{S i} \) | 4. | \(\left(E_g\right)_C<\left(E_g\right)_{S i}\) |
Subtopic: Â Energy Band theory |
 70%
From NCERT
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A \(\mathrm{p\text-n}\) photodiode is fabricated from a semiconductor with a band gap of \(2.5~\text{eV}.\) It can detect a signal of wavelength:
1. \(6000~\mathring{A}\)
2. \(4000~\text{nm}\)
3. \(6000~\text{nm}\)
4. \(4000~\mathring{A}\)
1. \(6000~\mathring{A}\)
2. \(4000~\text{nm}\)
3. \(6000~\text{nm}\)
4. \(4000~\mathring{A}\)
Subtopic: Â Energy Band theory |
 63%
From NCERT
AIPMT - 2009
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A semiconductor is known to have an electron concentration of \(8\times 10^{13}~\text{cm}^{-3},\) and a hole concentration of \(5\times 10^{2}~\text{cm}^{-3}.\) The semiconductor is:
| 1. | \(\mathrm{n}\text-\)type | 2. | \(\mathrm{p}\text-\)type |
| 3. | intrinsic | 4. | insulator |
Subtopic: Â Types of Semiconductors |
 87%
From NCERT
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\(\mathrm{C}\) and \(\mathrm{Si}\) both have the same lattice structure, having \(4\) bonding electrons in each. However, \(\mathrm{C}\) is an insulator whereas \(\mathrm{Si}\) is an intrinsic semiconductor. This is because:
| 1. | in the case of \(\mathrm{C},\) the valence band is not completely filled at absolute zero temperature. |
| 2. | in the case of \(\mathrm{C},\) the conduction band is partly filled even at absolute zero temperature. |
| 3. | the four bonding electrons in the case of \(\mathrm{C}\) lie in the second orbit, whereas in the case of \(\mathrm{Si},\) they lie in the third. |
| 4. | the four bonding electrons in the case of \(\mathrm{C}\) lie in the third orbit, whereas for \(\mathrm{Si},\) they lie in the fourth orbit. |
Subtopic: Â Energy Band theory |
 71%
From NCERT
NEET - 2012
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Pure \(\mathrm{Si}\) at \(500~\text K\) has an equal number of electrons \((n_i)\) and the hole \((n_h)\) concentration of \(1.5\times10^{16}~\text{m}^{-3}.\) Doping by indium increases the hole concentration \(n_h\) to \(4.5\times 10^{22}~\text{m}^{-3}.\) The doped semiconductor is of:
| 1. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=5\times10^{22}~\text{m}^{-3}\) |
| 2. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=2.5\times10^{23}~\text{m}^{-3}\) |
| 3. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=2.5\times10^{10}~\text{m}^{-3}\) |
| 4. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=5\times10^{9}~\text{m}^{-3}\) |
Subtopic: Â Types of Semiconductors |
 69%
From NCERT
NEET - 2011
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If the reverse bias in a junction diode is changed from \(5~\text V\) to \(15~\text V\) then the value of current changes from \(38~\mu \text{A}\) to \(88~\mu \text{A}.\) The resistance of the junction diode will be:
1. \(4\times10^{5}\)
2. \(3\times10^{5}\)
3. \(2\times10^{5}\)
4. \(10^{6}\)
Subtopic: Â PN junction |
 84%
From NCERT
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The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance \(R_1\) will be:
| 1. | \(2.5~\text A\) | 2. | \(10.0~\text A\) |
| 3. | \(1.43~\text A\) | 4. | \(3.13~\text A\) |
Subtopic: Â PN junction |
 86%
From NCERT
NEET - 2016
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What is the reading of the ideal ammeters \(A_1\) and \(A_2\) connected in the given circuit diagram, if \(\mathrm{p\text-n}\) junction diodes are ideal?
| 1. | \(2~\text A\) and zero | 2. | \(3~\text A\) and \(2~\text A\) |
| 3. | \(2~\text A\) and \(3~\text A\) | 4. | Zero and \(2~\text A\) |
Subtopic: Â PN junction |
 83%
From NCERT
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