Monostable 555 timer — how many stable states does it inherently have? Choose the number of stable states for a one-shot (monostable) configuration.

Introduction / Context:
A monostable multivibrator (one-shot) is designed to have a single stable state and one quasi-stable state. When triggered, it leaves its stable state temporarily and then returns, producing a pulse. This question checks conceptual understanding of the 555 in monostable mode.

Given Data / Assumptions:

• Device: 555 timer in monostable configuration
• Trigger produces one timing pulse
• After timing, the circuit returns to its resting state

Concept / Approach:
The defining property of a monostable is exactly one stable state. The other state exists only transiently (quasi-stable) during the output pulse interval set by R and C.

Step-by-Step Solution:

Verification / Alternative check:
Compare with astable (no stable state, constant oscillation) and bistable (two stable states, i.e., flip-flop). The monostable sits between them conceptually with exactly one stable state.

Why Other Options Are Wrong:

• 0: Describes astable oscillators, not monostables.
• 2 or 3 or 4: Would imply flip-flop behavior (two) or multi-stable systems; not applicable.

Common Pitfalls:

• Confusing monostable with astable or bistable due to naming similarity.

Final Answer:
1