An RC circuit as shown in the figure is driven by a AC source generating a square wave. The output wave pattern monitored by CRO would look close to :
(A)(see structure)
(B)(see structure)✓ Correct
(C)(see structure)
(D)(see structure)
Answer: (B)
Solution
The oscilloscope is connected across the capacitor, so it displays the capacitor voltage. That voltage cannot jump, because a sudden change would demand an infinite current through the resistor. Each time the square wave steps up, the capacitor charges towards the new level along V(1−e−t/RC), climbing steeply at first and flattening as it nears that level. When the drive steps down, the capacitor discharges along e−t/RC, falling steeply at first and then levelling off. The trace is accordingly a smooth repeating wave with no vertical edges, each cycle showing an exponential rise to a rounded crest followed by an exponential fall to a rounded trough.
JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Single correct option
