Question:medium

A full wave rectifier circuit with diodes (\(D_1\)) and (\(D_2\)) is shown in the figure. If input supply voltage \(V_{in} = 220 \sin(100 \pi t)\) volt, then at \(t = 15\) msec: 

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In a center-tapped full-wave rectifier, when the voltage across one half of the secondary transformer is positive, the corresponding diode conducts. When the input AC voltage reverses its polarity, the voltage across the other half of the secondary becomes positive, and the other diode conducts.
Updated On: Mar 26, 2026
  • \( D_1 \) is reverse biased, \( D_2 \) is forward biased
  • \( D_1 \) and \( D_2 \) both are forward biased
  • \( D_1 \) and \( D_2 \) both are reverse biased
  • \( D_1 \) is forward biased, \( D_2 \) is reverse biased
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The Correct Option is D

Solution and Explanation

To ascertain the diode biasing in a full-wave rectifier at \(t = 15\) ms, we first determine the input voltage at this instant. The input voltage is defined by the equation:

\[ V_{in} = 220 \sin(100 \pi t) \]

Substituting \(t = 15\) ms (equivalent to \(t = 0.015\) seconds):

\[ V_{in} = 220 \sin(100 \pi \times 0.015) \]

The argument of the sine function evaluates to:

\[ 100 \pi \times 0.015 = 1.5 \pi \]

Given that \(\sin(1.5 \pi) = -1\), the input voltage is calculated as:

\[ V_{in} = 220 \times (-1) = -220 \text{ volts} \]

In a full-wave rectifier, \(D_1\) is typically forward-biased and \(D_2\) reverse-biased during the positive half-cycle of the input. Conversely, during the negative half-cycle, the input voltage is negative, causing \(D_1\) to be reverse-biased and \(D_2\) to be forward-biased. At \(t = 15\) ms, the input voltage is \(-220\) volts, corresponding to the negative half-cycle. Therefore, \(D_1\) will be reverse-biased, and \(D_2\) will be forward-biased.

Consequently, the diode biasing is: \(D_1\) is reverse biased, \(D_2\) is forward biased.

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