A power MOSFET is suspected faulty. After discharging the gate, the drain-source reads 2,Omega with the ohmmeter regardless of probe direction. This indicates:

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Electronics Engineering QUESTION #11695

Question 1

A power MOSFET is suspected faulty. After discharging the gate, the drain-source reads $2\,\Omega$ with the ohmmeter regardless of probe direction. This indicates:

Normal — MOSFETs have a built-in body diode
The MOSFET is operating in the linear region
Drain-source channel is short-circuited — device failed✔️
The threshold voltage $V_{GS(th)}$ has been exceeded

Correct Answer Explanation

A healthy power MOSFET D-S should read OL in both directions (with gate discharged), except for the body diode which gives ~0.5–0.7 V forward drop in one direction. A symmetrically low resistance D-S reading in both directions indicates a drain-source short — typical of avalanche damage, overcurrent, or overvoltage failure.

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