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:  Energy Band theory |
 69%
From NCERT
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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:  Types of Semiconductors |
 87%
From NCERT
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If in a \(\mathrm{p\text-n}\) junction, a square input signal of \(10\) V is applied as shown, then the output across \(R_L\) will be:
              

1. 2.
3. 4.
Subtopic:  Rectifier |
 66%
From NCERT
NEET - 2015
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The given graph represents the \(V\text-I\) characteristic for a semiconductor device. Which of the following statement is correct?

1. It is a \(V\text-I\) characteristic for a solar cell where point \(A\) represents open-circuit voltage and point \(B\) represents short-circuit current.
2. It is for a solar cell and points \(A\) and \(B\) represent open-circuit voltage and current respectively.
3. It is for a photodiode and points \(A\) and \(B\) represent open-circuit voltage and current respectively.
4. It is for a LED and points \(A\) and \(B\) represent open-circuit voltage and short circuit current respectively.
Subtopic:  Applications of PN junction |
 68%
From NCERT
NEET - 2014
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Pure \(Si\) at \(500\) K has equal number of electron \((n_i)\) and hole \((n_h)\) concentration of \(1.5\times10^{16}~\text{m}^{-3}.\) Doping by indium increases \(n_h\) 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:  Types of Semiconductors |
 69%
From NCERT
NEET - 2011
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The electrical circuit used to get smooth output from a rectifier circuit is called:

1. oscillator.

2. filter.

3. amplifier.

4. logic gates.

Subtopic:  Rectifier |
 60%
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The correct symbol for zener diode is:

1. 2.
3. 4.
Subtopic:  Applications of PN junction |
 90%
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\({C}\) and \({Si}\) both have the same lattice structure, having \(4\) bonding electrons in each. However, \(C\) is an insulator whereas \(Si\) is an intrinsic semiconductor. This is because:
1. in the case of \(C\), the valence band is not completely filled at absolute zero temperature.
2. in the case of \(C\), the conduction band is partly filled even at absolute zero temperature.
3. the four bonding electrons in the case of \(C\) lie in the second orbit, whereas in the case of \(Si\), they lie in the third.
4. the four bonding electrons in the case of \(C\) lie in the third orbit, whereas for \(Si\), they lie in the fourth orbit.
Subtopic:  Energy Band theory |
 71%
From NCERT
NEET - 2012
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The figure shows a logic circuit with two inputs \(A\) and \(B\) and the output \(C\). The voltage waveforms across \(A\), \(B\), and \(C\) are as given. The logic circuit gate is:
   

1. \(\text{OR}\) gate
2. \(\text{NOR}\) gate
3. \(\text{AND}\) gate
4. \(\text{NAND}\) gate

Subtopic:  Logic gates |
 83%
From NCERT
AIPMT - 2012
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\(\mathrm{p\text-n}\) photodiode is fabricated from a semiconductor with a band gap of \(2.5\) eV. It can detect a signal of wavelength:
1. \(6000~\mathring{A}\)
2. \(4000\) nm
3. \(6000\) nm
4. \(4000~\mathring{A}\)  
Subtopic:  Energy Band theory |
 63%
From NCERT
AIPMT - 2009
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