When a JFET is driven to its cut-off region, its conductive channel becomes _____________?
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Answer: B. completely closed by the depletion region
Explanation
When a JFET is driven into its cut-off region, the expanding depletion regions completely merge across the conductive channel. This complete pinching of the channel stops all majority carrier current flow between the drain and source terminals. Sufficiently large reverse gate-source bias forces the depletion zones to meet and seal off the entire channel path. Depletion regions grow naturally around reverse-biased pn junctions as mobile charge carriers are swept away from the boundary. Cut-off voltage represents the specific gate bias level required to completely close the conductive channel in a JFET. Operating in the cut-off region allows field effect transistors to function as electronic switches in digital logic circuits.
Stating that the channel is at its widest point describes zero gate bias conditions rather than the cut-off state. Describing the channel as extremely narrow refers to partial pinch-off conditions rather than complete cut-off closure. Saying the channel is reverse biased misidentifies the physical structure since the gate-source junction is what experiences reverse bias.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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