GATE 2024 IN – Question 60
The switch SW shown changes from position 1 to 0 when $V_C$ changes from logic HIGH to LOW, and vice versa. The PMMC voltmeter bandwidth is 1 Hz. For $V_{sense}=2\sin(4000\pi t)$ V and $V_{ref}=4\sin(2000\pi t)$ V, its reading is ______ V (nearest integer). All components are ideal.
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Correct answer: 0 to 0
Explanation
The switch multiplies the 2 kHz sensed sinusoid by a ±1 square wave set by the 1 kHz reference. That square wave has only odd harmonics of 1 kHz, so no matching 2 kHz term exists to produce DC. The 1 Hz PMMC rejects the remaining AC; its average reading is **0 V**.