B) Give a reverse translation of the summary (from Russian into English).

Date: 2015-10-07; view: 591.

A) Translate the summary given by your group-mates from English into Russian.

Act as an interpreter.

Speaking

Choose some sentences from the text and transform them using Predicative Constructions with Participles.

For example: If a battery is connected across the crystal, holes are repelled from the positive end of the crystal and are caused to drift towards the junction. – A battery having been connected across the crystal, holes are repelled from the positive end of the crystal and are caused to drift towards the junction.

26. Summarize the text “The Forward-Biased P-N Junction” in 150 words using at least 4 cases of Predicative Constructions with Participles.

28. Translate the text “Reverse Biase” with a dictionary in writing paying attention to the use of Participial Constructions.

The term “reverse biased” is considered to be referred to how a diode is used in a circuit. A diode being reverse biased, the voltage at the cathode is higher than that at the anode. Therefore, no current will flow until the diode breaks down. Connecting the P-type region to the negative terminal of the battery and the N-type region to the positive terminal corresponds to reverse bias.

The P-type material having being connected to the negative terminal of the power supply, the 'holes' in the P-type material are pulled away from the junction, causing the width of the depletion zone to increase. Similarly, the N-type region being connected to the positive terminal, the electrons will also be pulled away from the junction. Therefore we see the depletion region widening, and it does so increasingly with increasing reverse-bias voltage. This increases the voltage barrier causing a high resistance to the flow of charge carriers thus allowing minimal electric current to cross the p–n junction.

The strength of the depletion zone electric field increased, the reverse-bias voltage increases. Once the electric field intensity increases beyond a critical level, the p–n junction depletion zone breaks-down and current begins to flow, usually by either the Zener or avalanche breakdown processes. Both of these breakdown processes are non-destructive and are reversible, as long as the amount of current flowing does not reach levels that cause the semiconductor material to overheat and cause thermal damage.

This effect is used to one's advantage in Zener diode regulator circuits. Zener diodes have a certain - low - breakdown voltage. A standard value for breakdown voltage is for instance 5.6V. This means that the voltage at the cathode can never be more than 5.6V higher than the voltage at the anode, because the diode will break down - and therefore conduct - if the voltage gets any higher. This effectively regulates the voltage over the diode.

Another application where reverse biased diodes are used is in Varicap diodes. The width of the depletion zone of any diode changes with voltage applied. This varies the capacitance of the diode.