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For the given logic circuit, which of the following inputs combination will make both LED-1 and LED-2 to glow? [Figure: A and B feed an OR gate. The OR output lights LED-1 (through a resistor to ground) and also feeds an AND gate whose other input is C. That AND output goes to a second AND gate whose other input is A (taken by a wire from the A input). The second AND output lights LED-2 through a resistor to ground.]

Asked in JEE Main 5th April 1st Shift 2026 · Gate combinations and truth tables

• (1) A=0,B=1,C=1
• (2) A=1,B=0,C=0
• (3) A=1,B=0,C=1
• (4) A=1,B=1,C=0

Step-by-step solution

Why the other options are wrong

• (1) LED-1 glows, but the last AND gate needs A=1, so LED-2 stays off.
• (2) With C=0 the first AND output is 0, so LED-2 stays off.
• (4) With C=0 the first AND output is 0, so LED-2 stays off.

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