Name: Energy Band Gap
Uploaded: 2019-07-19
Duration: 5 min 21 s
Description: We know that certain materials conduct electricity whereas some don’t. Has it got anything to do with their energy bandgap? Let’s find out in this video.

Question

Draw the circuit diagrams for half-wave and full-wave rectification done with a

p

n

- diodes. Explain the action of diodes. Draw the input and output waveforms.

Accepted Answer

The half-wave rectifier circuit. The circuit consists of a transformer, a p-n junction diode and a resistor. In a half-wave rectifier circuit, either a positive half or the negative half of the AC input is passed through while the other half is blocked. Only one half of the input wave reaches the output. Therefore, it is called half-wave rectifier. Here, a p-n junction diode acts as a rectifying diode.

During the positive half cycle:

When the positive half cycle of the ac input signal passes through the circuit, terminal A becomes positive with respect to terminal B. The diode is forward biased and hence it conducts. The current flows through the load resistor $R_{L}$ and the AC voltage developed across $R_{L}$ constitutes the output voltage V and the waveform of the diode current.

During the negative half cycle:

When the negative half cycle of the ac input signal passes through the circuit, terminal A is negative with respect to terminal B. Now the diode is reverse biased and does not conduct and hence no current passes through $R_{L}$ . The reverse saturation current in a diode is negligible. Since there is no voltage drop across $R$ , the negative half cycle of ac supply is suppressed at the output. The output of the half-wave rectifier is not a steady dc voltage but a pulsating wave. This pulsating voltage is not sufficient for electronic equipments. A constant or a steady voltage is required which can be obtained with the help of filter circuits and voltage regulator circuits. Efficiency ( $η$ ) is the ratio of the output dc power to the ac input power supplied to the circuit. Its value for half-wave rectifier is 40.6 %.

During the positive half cycle of AC input voltage, the diode D₁ is forward biased and diode D₂ is reverse biased. During the negative half cycle of AC input voltage, the diode D₂ is forward biased and diode D₁ is reverse biased. During both the case the current in the external circuit flows in the same direction. That is a unidirectional current is obtained using a full-wave rectifier.

Draw the circuit diagrams for half-wave and full-wave rectification done with a $p$ $n$ - diodes. Explain the action of diodes. Draw the input and output waveforms.

Important Questions on Electronic Devices

Learn and Prepare for any exam you want !

Draw the circuit diagrams for half-wave and full-wave rectification done with a pn- diodes. Explain the action of diodes. Draw the input and output waveforms.

Important Questions on Electronic Devices

Learn and Prepare for any exam you want !

Draw the circuit diagrams for half-wave and full-wave rectification done with a $p$ $n$ - diodes. Explain the action of diodes. Draw the input and output waveforms.