The band gap between the valence band and the conduction band in a certain material is $$3$$ 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 $$hc$$=$$1240$$ eV-nm.)
 1 $$414$$ nm 2 $$300$$ nm 3 $$830$$ nm 4 $$207$$ nm
Subtopic:  Energy Band theory |
87%
From NCERT
Hints

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 |
86%
From NCERT
Hints

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 |
84%
From NCERT
Hints

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 |
78%
From NCERT
Hints

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%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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 |
74%
From NCERT
AIPMT - 2007
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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 |
77%
From NCERT
Hints

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
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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 |
73%
From NCERT
NEET - 2022
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch