🔍 Key Concepts

• Positive voltage on this diagram is shown by the parts of the waveform that lie above the dashed horizontal reference line. • In a pulse (square) waveform, there are rising edges, flat (steady) sections, and falling edges. • The question asks for the time interval when the pulse is steadily at a positive value, not when it is transitioning.

💭 Think About

• Look closely at figure B and identify which numbered line segment is completely above the dashed reference line for some period of time, rather than just crossing it. • Separate the vertical edges (where the voltage is changing quickly) from the horizontal parts (where the voltage is held constant). Which of the numbered lines is a horizontal, constant, positive level? • Consider what happens to the voltage during the lower part of the pulse. Which numbered lines clearly represent the negative or low interval so you can rule them out?

✅ Before You Answer

• Verify which parts of the waveform in figure B lie above the dashed line (positive) and which lie below it (negative). • Confirm that the correct choice is a segment where voltage is constant over time (horizontal), not a rapid change (vertical edge). • Double‑check that the segment you choose represents the duration of the high pulse, not just the instant where it rises or falls.