Question

The gate voltage in a JFET at which drain current becomes zero is called _______.

• A. Saturation voltage
• B. Pinch-off voltage
• C. Cut-off voltage
• D. Active voltage

Hint:

Pinch-off voltage is when JFET’s channel is fully depleted—no current flows through the device.

Answer 1

The Correct Option is B

Step 1: Definition
Pinch-off voltage ($V_P$) is the gate-source voltage at which the conductive channel of a JFET closes completely and $I_D$ becomes zero. 
Step 2: Physical meaning
Beyond $V_P$, increasing $|V_{GS}|$ will not further increase current, as the channel is completely pinched off. 
Step 3: Common mistake
Saturation voltage refers to when $I_D$ becomes constant, not zero. 
Conclusion: The correct term for the gate voltage where current stops is the pinch-off voltage.