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. p-type semiconductor
2. insulator
3. metal
4. n-type semiconductor

Subtopic:  Energy Band theory |
 75%
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 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:  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:  Energy Band theory |
 71%
From NCERT
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p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength:
1. 6000 Å
2. 4000 nm
3. 6000 nm
4. 4000 Å
 
Subtopic:  Energy Band theory |
 62%
From NCERT
AIPMT - 2009
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A semiconductor is known to have an electron concentration of 8×1013 cm-3 and a hole concentration of 5×102 cm-3. The semiconductor is:

1.  n-type

2.  p-type

3.  intrinsic

4.  insulator

Subtopic:  Types of Semiconductors |
 88%
From NCERT
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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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Pure Si at 500 K has equal number of electron (ne) and hole (nh) concentration of 1.5×1016 m-3. Doping by indium increases nh to 4.5×1022 m-3. The doped semiconductor is of:

1. n-type with electron concentration \(n_{e}=5\times10^{22}~m^{-3}\)
2. p-type with electron concentration \(n_{e}=2.5\times10^{23}~m^{-3}\)
3. n-type with electron concentration \(n_{e}=2.5\times10^{10}~m^{-3}\)
4. p-type with electron concentration \(n_{e}=5\times10^{9}~m^{-3}\)
Subtopic:  Types of Semiconductors |
 69%
From NCERT
NEET - 2011
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If the reverse bias in a junction diode is changed from \(5\) V to \(15\) V then the value of current changes from \(38\) \(\mu \text{A}\) to \(88\) \(\mu \text{A}.\) The resistance of junction diode will be:
1. \(4\times10^{5}\) 
2. \(3\times10^{5}\)
3. \(2\times10^{5}\)
4. \(10^{6}\)

Subtopic:  PN junction |
 85%
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 R1 will be:
     

1. 2.5 A 2. 10.0 A
3. 1.43 A 4. 3.13 A
Subtopic:  PN junction |
 87%
From NCERT
NEET - 2016
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What is the reading of the ideal ammeters A1 and A2 connected in the given circuit diagram, if p-n junction diodes are ideal?

   

1. 2 A and zero

2. 3 A and 2 A

3. 2 A and 3 A

4. Zero and 2 A

Subtopic:  PN junction |
 83%
From NCERT
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