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Voltage regulation is am important factor of a power supply. Regulation is its ability to hold the dc output steady under conditions of changing ac input or changing load. The output voltage under no-load condition (no current drawn from the supply) tends to drop to a lower value when load current is drawn from the supply (under load). The amount the dc voltage changes between the no-load and full-load conditions is described by a factor called voltage regulation. 

Voltage regulation = \(\cfrac{no-load \,voltage − full-load \,voltage}{full-load \,voltage}\)

Correct option is (A) makes logical decisions

(A) any one or more of the inputs is LOW

It is an OR gate.

I will include the following lessons for my security guard’s training for a better emergency response: 

A. Monitoring of surveillance and alarm systems 

B. Responding to alarms 

C. Responding to emergency situations 

D. Informing details of the incidents to the concerned appointments 

E. Seeking help from the emergency services 

F. Rescue and first-aid to the victims 

G. Co-operation with emergency services

For use as an amplifier, the transistor should be in active mode. Therefore, the emitter-base junction is forward biased and the collectorbase junction is reverse biased. Also, an amplifier uses an emitter bias rather than a base bias.

A junction transistor consists of two back-toback pn-junctions forming a sandwich structure in which a thin layer of n-type or ptype semiconductor is sandwiched between two layers of opposite type semiconductor.

The three terminals of a transistor connected to its three layers are known as the emitter (E), base (B) and collector (C). One pn-junction is between the emitter and the base while the other pn-junction is between the collector and the base.

The electric current is transported by both type of carriers, electrons and holes; for this reason the device is called a bipolar junction transistor (BJT).

There are two types of junction transistors : 

(i) pnp transistor 

(ii) npn transistor.

[Note : The point-contact transistor was invented in 1947 by US physicists John Bardeen (1908-91), Walter Brattain (1902-87) and William Shockley (1910-89). A month later Shockley invented the junction transistor.]

1. The process of converting an alternating voltage (or current) to a direct voltage (or current) is called rectification. A circuit or device that is used to convert an alternating voltage (or current) to a direct voltage (or current) is called a rectifier. A rectifier produces a unidirectional but pulsating voltage from an alternating voltage. 

2. When an alternating voltage is applied across a pn-junction diode, the diode is forward-biased and reverse-biased during alternate half cycles. 

3. During the half cycle when the diode is forward- – biased, it conducts. Therefore, there is a current through it from the p-region to the n-region. 

4. During the next half cycle, it is reversebiased and does not conduct. Therefore, current passes only in one direction through the circuit. This way, a pn-junction diode acts as a rectifier.

PN-junction diode: A two-terminal semiconductor device consisting of a PNjunction is called a PN- junction diode. Depletion region: The neighbourhood of the junction between a p-type layer and an n-type layer within a single semiconducting crystal is depleted of free (or mobile) charge carriers. This is called the depletion region or depletion layer. 

Barrier potential: The electric potential difference across the PN-junction is called the potential barrier or barrier potential. 

[Note: Under the open-circuit condition (no applied potential difference), the width of the depletion region and the height of the potential barrier have their equilibrium values. The width of the depletion region in an unbiased pn-junction diode ranges from 0.5 pm to 1 pm and depends on the dopant concentrations. The barrier potential is about 0.3 V for Ge junction diode and about 0.7 V for Si junction diode.]