Question

PN-junction diode works as an insulator when connected in?

• A. To A.C
• B. In forward bias
• C. In reverse bias
• D. None of these

Answer 1

The correct option is C

In reverse bias

PN junction

1. A PN junction has the property of exclusively transferring current in one direction.
2. A diode, unlike a resistor, does not work linearly with respect to the applied voltage because it generates an exponential current-voltage relationship.
3. A two-terminal PN junction, the diode can be used in a variety of applications. An electrical switch is one such application. When forward biassed, the PN terminal acts as a close circuit, whereas when reverse bias, acts as an open circuit.
4. As a result of the variation of forward and reverse biassed states, the diode acts as a switch, with the forward state being ON and the reverse state being OFF.

The explanation of the correct option.

In the case of option C.

1. In reverse biased, $R=\infty$. P-N junction gives high resistance when connected in reverse biased.
2. When a p-n junction diode is used to block electric current from flowing in the presence of applied voltage, it is called a reverse-biased p-n terminal diode. When reverse bias, it offers a large impedance, so there will be no current draw.
3. In a reverse-biased p-n junction diode, the n-type semiconductor is connected to the positive terminal of the battery, while the p-type semiconductor is connected to the negative terminal. When a PN junction diode is used in reverse bias, it produces zero current and acts as an insulator.

The explanation of the incorrect option.

In the case of option A

When a diode is connected to an AC supply, the diode just passes the current based on the biasing. In this case, it just simply acts as a halfwave rectifier.

In the case of option C

1. In forward biased, $R=0$. P-N junction gives low resistance when connected in forward biased.
2. When a diode is forward biassed, it carries current, so there will be a current draw in the circuit

In the case of option D

1. As we have got option C as the correct answer. Therefore this option cannot be true.

Hence, option C is correct answer