NABTEB 2023 Electronics Works Essays $ Objective Questions And Answers

1a
i)Intrinsic semiconductor is a pure semiconductor in which number of holes is equal to number of electrons.
ii)Extrinsic semiconductors are semiconductors that are doped with specific impurities.
iii)A transistor is a semiconductor device used to amplify or switch electronic signals.

1bi) diagram

1bii)
Stablizer;
i) take under/over voltage clue from the input
ii) voltage drop due to load not considered

Regulator;
i) take feedback from input
ii) regulate voltage precisely to the desire value

2ai. An electronic circuit is a system of interconnected electronic components that perform a specific function.

2aii. The three types of electronic circuits are:
– Series circuit
– Parallel circuit
– Combination circuit

Five types of electronic devices are:
– Transistors
– Diodes
– Resistors
– Capacitors
– Inductors

2b.

2c.
– Cathode Ray Tube: A vacuum tube used to display images.
– Photoelectric Devices: Devices that convert light energy into electrical energy.
– Integrated Circuits: Miniaturized electronic circuits consisting of interconnected components on a single chip.

3a.

– Rectifier diode: Converts AC to DC.
– Zener diode: Regulates voltage.
– Light-emitting diode (LED): Emits light when current passes through it.
– Schottky diode: Used for high-speed switching applications.
– Varactor diode: Alters capacitance based on applied voltage.

3b. Semiconductor devices are electronic components made from semiconductor materials that exhibit specific electrical behavior.

Three types of semiconductor devices:
– Diodes
– Transistors
– Integrated circuits

Doped semiconductors are semiconductors that have impurities intentionally added to modify their electrical properties.

3c.
– Zener Diode: A specialized diode that operates in the reverse breakdown region to maintain a constant voltage.
– Tunnel Diode: A diode that exhibits negative resistance and is used for high-frequency oscillators and amplifiers.
– Field Effect Transistor (FET): A transistor that uses an electric field to control the conductivity of a channel.
– Oscilloscope: An electronic instrument used to visualize and analyze electrical signals.
– Oscillator: An electronic circuit that generates a continuous waveform

4a)
i) An amplifier is an electronic device that increases the voltage, current, or power of a signal.

4aii)Class A ; design is the least efficient but has the highest sound fidelity.
Class B ; design is a little more efficient, but has a lot of distortion.
Class AB ; design packs a punch with power efficiency and superb sound.
Class D ; design offers the highest efficiency but isn’t quite as high-fidelity.

4aiii)
i. Gain stability decreases
ii. Noise and distribution increases
iii. Drcreases bandwit

4bi)
Amplitude Modulation
i)The radio wave is called a carrier wave, and the frequency and phase remain the same
ii)Has poor sound quality, but can transmit longer distance
iii) The frequency range of AM radio varies from 535 to 1705 kHz
iv) More susceptible to noise

Frequency Modulation
i)The radio wave is called a carrier wave, but the amplitude and phase remain the same
ii)Has higher bandwidth with better sound quality
iii)The frequency range of FM is 88 to 108 MHz in the higher spectrum
iv)Less susceptible to noise

Completed………….