The band gap between the valence band and the conduction band in a certain material is \(3~\text{eV}.\) What is the longest wavelength of light that can create an electron-hole pair in the material, with the electron in the conduction band and the hole in the valence band?
(take \(hc=1240~\text{eV-nm}\) )
1. \(414~\text{nm}\)
2. \(300~\text{nm}\)
3. \(830~\text{nm}\)
4. \(207~\text{nm}\)
Subtopic:  Energy Band theory |
 88%
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The energy band gap of semiconducting material to produce violet (wavelength \(=4000~\mathring{A}\)) LED is (nearly):
1. \(3~\text{eV}\)
2. \(5~\text{eV}\)
3. \(1~\text{eV}\)
4. \(7~\text{eV}\)
Subtopic:  Energy Band theory |
 89%
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When semiconductor is heated, its resistance:
1. decreases
2. increases
3. remains the same
4. may increase or decrease depending on the semiconductor
Subtopic:  Energy Band theory |
 86%
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Specify which of the following type of material might satisfy these descriptions:
A half-filled valence band, an empty conduction band, and an energy gap of \(1\) eV.
1. conductor
2. insulator
3. semiconductor
4. none of the above
Subtopic:  Energy Band theory |
 79%
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In a good conductor, the energy gap between the conduction band and the valence band is:
1. Infinite
2. Wide
3. Narrow
4. Zero

Subtopic:  Energy Band theory |
 77%
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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:  Energy Band theory |
 80%
From NCERT
AIPMT - 2005
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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:  Energy Band theory |
 75%
From NCERT
AIPMT - 2007
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A semiconductor has a negative temperature coefficient of:
1. resistance
2. conductance
3. both resistance and conductance
4. neither resistance nor conductance
Subtopic:  Energy Band theory |
 80%
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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 |
 70%
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As the temperature increases, the electrical resistance:
1. decreases for conductors but increases for semiconductors.
2. increases for both conductors and semiconductors.
3. decreases for both conductors and semiconductors.
4. increases for conductors but decreases for semiconductors.
Subtopic:  Energy Band theory |
 74%
From NCERT
NEET - 2022
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