Semiconductor Electronics

[figure] To obtain the given truth table, following logic gate should be placed at G :

1. NOR Gate
2. OR Gate
3. AND Gate
4. NAND Gate

A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is 1.42 eV. The wavelength of light emitted from the LED is :

1. 1243 nm
2. 875 nm
3. 650 nm
4. 1400 nm

[figure] In the truth table of the above circuit the value of X and Y are :

1. 1, 1
2. 0, 1
3. 1, 0
4. 0, 0

The I–V characteristics of an electronic device are shown in the figure. The device is : [figure]

1. a solar cell
2. a transistor which can be used as an amplifier
3. a diode which can be used as a rectifier
4. a zener diode which can be used as a voltage regulator

The output Y of following circuit for given inputs is : [figure]

1. A B
2. A B
3. A B(A + B)
4. 0

A potential divider circuit is connected with a dc source of 20 V, a light emitting diode of glow in voltage 1.8 V and a zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is cm. [figure]

The correct truth table for the following logic circuit is : [figure]

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The acceptor level of a p-type semiconductor is 6 eV. The maximum wavelength of light which can create a hole would be : Given hc = 1242 eV nm.

1. 407 nm
2. 103.5 nm
3. 414 nm
4. 207 nm

Following gates section is connected in a complete suitable circuit. [figure] For which of the following combination, bulb will glow (ON) :

1. A = 1, B = 1, C = 1, D = 0
2. A = 1, B = 0, C = 0, D = 0
3. A = 0, B = 0, C = 0, D = 1
4. A = 0, B = 1, C = 1, D = 1

The output (Y) of logic circuit given below is 0 only when : [figure]

1. A = 0, B = 0
2. A = 0, B = 1
3. A = 1, B = 0
4. A = 1, B = 1