UJT negative-resistance region A UJT (unijunction transistor) exhibits negative resistance between which current levels on its characteristic?

Introduction / Context:The UJT is a popular triggering device whose emitter characteristic features a negative-resistance region. Understanding where this region lies relative to the peak and valley points is important for designing relaxation oscillators and trigger circuits for thyristors.

Given Data / Assumptions:

• Standard UJT E–I characteristic with clearly defined peak and valley points.
• Terminology: I_P (peak current), I_V (valley current).

Concept / Approach:

As the emitter voltage rises to the peak point, the UJT fires and enters a region where emitter voltage drops while emitter current increases—this is the negative-resistance region. The characteristic continues until the valley point is reached; below the valley current the device reverts to the high-resistance (off) state.

Step-by-Step Solution:

Verification / Alternative check:

Reference UJT curves show the slope dV/dI negative between the peak and valley points (I_P < I < I_V).

Why Other Options Are Wrong:

• “Less than valley current” or “less than peak current” do not correspond to the negative-resistance segment; these are in off-region or pre-trigger region.
• “None”: incorrect because the negative-resistance range is well defined between I_P and I_V.

Common Pitfalls:

Assuming valley current is smaller than peak current conceptually; numerically I_V is typically greater than I_P on the I–V plot of a UJT.

Final Answer:

Current is more than peak current but less than valley current