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MCQEasyJEE 2025Diodes & Rectifiers

JEE Physics 2025 Question with Solution

The output voltage in the following circuit is (Consider ideal diode case):

Circuit with two diodes D1 and D2 connected to a common output node Vout, one branch from +5 V, one from ground, and a resistor from the output node upward to +5 V.
  • A

    −5 V-5 \, V

  • B

    +5 V+5 \, V

  • C

    10 V10 \, V

  • D

    0 V0 \, V

Answer

Correct answer:D

Step-by-step solution

Standard Method

Given: The circuit contains ideal diodes D1D_1 and D2D_2. Ideal diodes conduct when forward biased and do not conduct when reverse biased.

Find: The output voltage VoutV_{\text{out}}.

From the solution text, analyze the diode states:

  1. D1D_1 is forward biased, so it conducts as an ideal diode.
  2. D2D_2 is reverse biased, so it does not conduct.
  3. The conducting diode pulls the output node to ground potential in this circuit.

Therefore, the output voltage is 0 V0 \, V. The correct option is D.

The solution contains some inconsistent intermediate wording mentioning +5 V+5 \, V, but its final conclusion explicitly states that the output voltage is 0 V0 \, V, and the listed correct option is D.

Using the diode-bias argument from the hint

Given: For ideal diodes, a forward-biased diode has zero voltage drop and a reverse-biased diode behaves like an open circuit.

Find: The value of VoutV_{\text{out}}.

Use the hint from the solution: the conducting diode pulls the output voltage to 0 V0 \, V.

So, the node at VoutV_{\text{out}} is clamped to ground potential, while the other diode remains non-conducting.

Hence, the output voltage is 0 V0 \, V and the correct option is D.

Common mistakes

  • Assuming both diodes conduct simultaneously. That is wrong because ideal diode conduction depends on biasing. First determine which diode is forward biased and which is reverse biased, then find the node voltage.

  • Taking the resistor connection to +5 V+5 \, V as sufficient to force Vout=+5 VV_{\text{out}} = +5 \, V. This is wrong because a conducting ideal diode can clamp the node. Always check whether the node is being held at ground or supply through an ideal diode.

  • Ignoring the final conclusion of the solution and focusing only on an inconsistent intermediate sentence. When the working text has a contradiction, use the explicit final conclusion and stated correct option to identify the answer.

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