CET Electronic Components and Devices 3

Question 1

Which parameter of a MOSFET is analogous to the transconductance of a BJT?

Accepted Answer

Transconductance (gm)

Answer

Transconductance (gm) relates the change in drain current to the change in gate-source voltage in a MOSFET.

Question 2

A photodiode is operated in which mode for fastest response time?

Accepted Answer

Reverse bias (photoconductive mode)

Answer

Reverse bias (photoconductive mode) widens the depletion region, reducing junction capacitance and speeding up response.

Question 3

What causes thermal runaway in a bipolar junction transistor?

Accepted Answer

Increased collector current raising junction temperature, further increasing current

Answer

Rising temperature increases leakage current, which raises collector current, generating more heat in a destructive positive feedback loop.

Question 4

Which type of capacitor is NOT polarized and is commonly used in AC filtering applications?

Accepted Answer

Film (polyester)

Answer

Film capacitors are non-polarized and suitable for AC circuits, whereas electrolytic and tantalum types are polarized.

Question 5

In an enhancement-mode N-channel MOSFET, current flows when the gate-source voltage (VGS) is:

Accepted Answer

Above threshold voltage

Answer

An enhancement-mode N-channel MOSFET requires VGS to exceed the threshold voltage to create the conducting channel.

(CET) Certified Electronics Technician Practice Test