Field Effect Transistors (FET/JFET/MOSFET) — A/L Physics

How do I practise Field Effect Transistors (FET/JFET/MOSFET)?

1 question with a worked solution

1. What is the primary operational distinction between a Field Effect Transistor (FET) and a Bipolar Junction Transistor (BJT)?
   1. A) FET is a unipolar voltage-controlled device with extremely high input impedance, whereas BJT is a bipolar current-controlled device
   2. B) FET has zero pinch-off voltage and negative breakdown resistance
   3. C) BJT utilizes only majority carriers, whereas FET utilizes both electrons and holes simultaneously
   4. D) BJT has infinite gate resistance, whereas FET requires high continuous gate current
   Check my answer

   Correct answer: A) FET is a unipolar voltage-controlled device with extremely high input impedance, whereas BJT is a bipolar current-controlled device

   A FET is a unipolar device wherein conduction is governed by one type of carrier (electrons in n-channel, holes in p-channel) controlled by the electric field (gate voltage V_GS), yielding nearly infinite input impedance. BJTs are current-controlled (I_B governs I_C) and rely on both electrons and holes (bipolar).

   Show worked solution

   Step 1: FET: Voltage-controlled, unipolar (majority carriers only), high input impedance. Step 2: BJT: Current-controlled, bipolar (both carriers). Answer: FET is a unipolar voltage-controlled device with extremely high input impedance, whereas BJT is a bipolar current-controlled device.
   Modelled on: the A/L Physics examination pattern

Get this auto-marked

Next in the syllabus

Where does Field Effect Transistors (FET/JFET/MOSFET) fit in the syllabus?

Unit 9.5 · Year 2 · Term 2