UJT (uni-junction transistor) characteristic Between which characteristic points does a UJT exhibit its negative-resistance region?

Introduction / Context:
The UJT is widely used in relaxation oscillators and triggering circuits because of its negative-resistance region in the V–I characteristic. Recognizing the interval over which negative resistance exists is key to designing timing and triggering networks.

Given Data / Assumptions:

• Standard UJT emitter characteristic with peak point (Vp, Ip) and valley point (Vv, Iv).
• Device biased with emitter referenced to the base resistor network.

Concept / Approach:
As the emitter voltage is increased to the peak point, the device enters conduction; beyond this point, the emitter voltage actually drops with increasing current until the valley point—this is the negative-resistance region. After the valley point, the device behaves in a low-resistance regime.

Step-by-Step Solution:
Increase Ve from zero to Vp: current rises slowly to Ip (no negative resistance yet).From peak (Vp, Ip) to valley (Vv, Iv): dV/dI is negative—negative-resistance behavior.Beyond the valley point: the device transitions to a quasi-ohmic low-resistance state.

Verification / Alternative check:
Typical datasheets and textbooks plot the V–I curve showing the negative-resistance stretch explicitly between peak and valley.

Why Other Options Are Wrong:
Before peak / after valley only: Regions are not negative-resistance.
After peak only (without valley limit): Incomplete; the region ends at the valley point.

Common Pitfalls:
Confusing the trigger point (peak) with the entire operating range; stable oscillation relies on designing around the peak–valley segment.

Final Answer:
between peak and valley points