A single phase half wave rectifier is feeding a resistive load. As firing angle is increaseda)dc output voltage and rms output voltage decrease in the same proportionb)dc output voltage and rms output voltage decreasec)dc output voltage and rms output voltage increased)dc output voltage and rms output voltage increase in the same proportionCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Explanation:
A single phase half wave rectifier is a circuit that converts an alternating current (AC) input into a direct current (DC) output. It consists of a diode and a load resistor. The firing angle is the delay between the instant when the diode is forward biased and the instant when the diode conducts current.

Effect of increasing firing angle:
When the firing angle is increased, the conduction period of the diode decreases. This means that the diode conducts current for a shorter duration during each half-cycle of the AC input waveform.

Effect on DC output voltage:
The DC output voltage of a single phase half wave rectifier is the average value of the rectified waveform. As the firing angle is increased, the duration of conduction decreases, resulting in a smaller area under the rectified waveform. This leads to a decrease in the average value of the waveform, i.e., the DC output voltage.

Effect on RMS output voltage:
The RMS (Root Mean Square) output voltage of a single phase half wave rectifier is a measure of the effective value of the rectified waveform. The RMS value is directly proportional to the square root of the area under the rectified waveform. As the firing angle is increased and the conduction period decreases, the area under the waveform decreases. This leads to a decrease in the RMS value of the waveform, i.e., the RMS output voltage.

Conclusion:
Based on the above explanation, it can be concluded that when the firing angle is increased in a single phase half wave rectifier, both the DC output voltage and the RMS output voltage decrease. Therefore, the correct answer is option 'B'.

Answer

Introduction:
A single-phase half-wave rectifier is a circuit that converts an alternating current (AC) input into a direct current (DC) output. It consists of a diode and a load resistor. The firing angle refers to the delay between the start of the AC input cycle and the triggering of the diode.

Explanation:
When the firing angle of a single-phase half-wave rectifier is increased, it affects both the DC output voltage and the RMS output voltage. Let's understand how:

1. DC Output Voltage:
The DC output voltage of a rectifier is the average value of the rectified waveform. It is given by the formula:

Vdc = (2 / π) * Vm * sin(α)

Where:
Vdc = DC output voltage
Vm = Peak value of the input AC voltage
α = Firing angle

As the firing angle is increased, the conduction period of the diode decreases. This means that the diode conducts for a shorter duration during each input cycle. Consequently, the average value of the rectified waveform decreases, leading to a decrease in the DC output voltage.

2. RMS Output Voltage:
The RMS (Root Mean Square) output voltage of a rectifier is the effective value of the rectified waveform. It is given by the formula:

Vrms = Vm / √(2π) * (1 - cos(α))

Similar to the DC output voltage, the RMS output voltage is also affected by the firing angle. As the firing angle increases, the conduction period decreases, resulting in a decrease in the effective value of the rectified waveform. Therefore, the RMS output voltage also decreases.

Conclusion:
Based on the above explanations, it can be concluded that as the firing angle of a single-phase half-wave rectifier is increased, both the DC output voltage and the RMS output voltage decrease. Therefore, the correct answer is option 'B'.

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