The conductivity of a semiconductor increases with an increase in temperature because:

1. number density of free current carriers increases

2. relaxation time increases

3. both number density of carriers and relaxation time increase

4. number density of carriers increases, relaxation time decreases but the effect of decrease in relaxation time is much less than the increase in number density

A 220 V AC supply is connected between points A and B (figure). What will be the potential difference V across the capacitor?

1. 220 V

2. 110 V

3. 0 V

4. $220\sqrt{2}$V

Write the name of the following gate that the circuit shown in figure.

1. AND gate

2. OR gate

3. NOr gate

4. XOR gate

The reverse bias in a junction diode is changed from 8 V to 13 V, then the value of the current changes from $40 \mathrm{\mu } \mathrm{A} \mathrm{to} 60 \mathrm{\mu } \mathrm{A}$. The resistance of the junction diode will be: 

1. $2\times {10}^5 \Omega$

2. $2.5\times {10}^5 \Omega$

3. $3\times {10}^5 \Omega$

4. $4\times {10}^5 \Omega$

A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be:

1. a p-type semiconductor

2. an n-type semiconductor

3. a p-n junction

4. an intrinsic semiconductor

If in a p-n junction diode, a square input signal of 10 V is applied as shown

Then the output signal across ${\mathrm{R}}_{\mathrm{L}}$ will be

1. 

2. 

3. 

4. 

In the given figure, a diode D is connected to an external resistance R=100$\Omega$ and an e.m.f. of 3.5 V. If the barrier potential developed across the diode is 0.5 V, the current in the circuit will be:

1. 30 mA

2. 40 mA

3. 20 mA

4. 35 mA

The input signal is given to a CE amplifier having a voltage gain of 150 is ${\mathrm{V}}_{\mathrm{i}}=2\cos \left[15\mathrm{t}+\frac{{\displaystyle \mathrm{II}}}{{\displaystyle 3}}\right]$. The corresponding output signal will be:

1. $30 \cos \left[15t+\frac{\mathrm{\pi }}{3}\right]$

2. $75 \cos \left[15t+\frac{2\mathrm{\pi }}{3}\right]$

3. $2 \cos \left[15t+\frac{5\mathrm{\pi }}{3}\right]$

4. $300 \cos \left[15t+\frac{4\mathrm{\pi }}{3}\right]$

The battery is shown in the figure, current drawn from the battery is:

1.  1 A

2.  2 A

3.  2.5 A

4.  4 A