Semiconductor Electronics PYQ | Ideal Diode Circuit | JEE Main 2025

 

❓ Question

For the following circuit, assuming ideal diodes, determine the output voltage $V_{\text{out}}$.

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✍️ Solution

For an ideal diode:

• Forward biased (ON): Acts as a short circuit $(V_D=0)$.
• Reverse biased (OFF): Acts as an open circuit $(I=0)$.

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Check Diode $D_1$

The anode of $D_1$ is connected to

$$+5\text{ V}.$$

If

$$V_{\text{out}}=+5\text{ V},$$

then the cathode of $D_1$ is also at

$$+5\text{ V}.$$

Hence,

$$V_{\text{anode}}=V_{\text{cathode}}.$$

Therefore,

$$\boxed{D_1\ \text{is OFF}.}$$

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Check Diode $D_2$

The anode of $D_2$ is connected to

$$0\text{ V (Ground)}.$$

The cathode is at

$$V_{\text{out}}=+5\text{ V}.$$

Thus,

$$V_{\text{anode}}<V_{\text{cathode}},$$

so $D_2$ is reverse biased.

Hence,

$$\boxed{D_2\ \text{is OFF}.}$$

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Output Voltage

Since both diodes are OFF, no current flows through either diode.

The output node remains directly connected to the

$$+5\text{ V}$$

supply.

Therefore,

$$V_{\text{out}}=+5\text{ V}.$$

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✅ Final Answer

$$\boxed{V_{\text{out}}=+5\ \text{V}}$$