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.

Application of a forward bias to a p-n junction:

Of the diodes shown in the following diagrams, which one of the diodes is reverse biased?
 

1.		2.
3.		4.

In semiconductors at room temperature:

The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without a filter is \(10\) V. The d. c. component of the output voltage is:
1. \(\frac{10}{\pi }\) V
2. \(10\) V
3. \(\frac{20}{\pi }\) V
4. \(\frac{10}{\sqrt{2}}\) V

For the given circuit of the P-N junction diode, which of the following statements is correct?

Reverse-bias applied to a junction diode:

The barrier potential of a p-n junction diode does not depend on:

1. diode design

2. temperature

3. forward bias

4. doping density

The V-I characteristic of a silicon diode is shown in the figure. The resistance of the diode at ${\mathrm{I}}_{\mathrm{D}}=15 \mathrm{mA}$ is: 

$1. 20 \mathrm{\Omega }$
$2. 30 \mathrm{\Omega }$
$3. 15 \mathrm{\Omega }$
$4. 10 \mathrm{\Omega }$

Hole is: