The following table 
 
is a truth table for

1. NAND gate

2. NOR gate

3. XOR gate

4. AND gate

Transfer characteristics [output voltage (${\mathrm{V}}_{\mathrm{o}}$) vs input voltage (${\mathrm{V}}_{\mathrm{i}}$)] for a base biased transistor in CE configurations are as shown in the figure. For using the transistor as a switch, it is used:

1. In region III

2. Both in the region (I) and (III)

3. In region II

4. In region I

To get an output Y = 1 from the circuit shown below, the input must be:

1. A=0 B=1 C=0

2. A=0 B=0 C=1

3. A=1 B=0 C=1

4. A=1 B=0 C=0

A p-n photodiode is made of a material with a bandgap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly:

1. $10\times {10}^{14}$ $\mathrm{Hz}$

2. $5\times {10}^{14}$ $\mathrm{Hz}$

3. $1\times {10}^{14}$ $\mathrm{Hz}$

4. $20\times {10}^{14}$ $\mathrm{Hz}$