Question

1. diodes are commonly used inside a vehicles charging system ______ to rectify ac voltage to dc voltage.

1. what type of diode is a special type of diode that serves as a voltage regulator?

(a) forward bias
(b) reverse bias
(c) rectified
(d) zener

1. a(n)______ is a semiconductor device that regulates current or voltage in a circuit.

1. a bipolar junction transistor (bjt) is made by joining ______ semiconductor materials.

(a) two
(b) three
(c) four
(d) five

1. what is the difference between an npn transistor and a pnp transistor?

1. identify the types of transistors shown below.

emitter $longleftrightarrow$ collector emitter $longleftrightarrow$ collector
(a) ______
(b) ______
base base
a b

1. explain the similarities and differences between a transistor and a relay.

1. a ______ device produces a low current output when physical pressure is applied.

(a) light emitting diode (led)
(b) photonic
(c) piezoelectric crystal
(d) photovoltaic cell

1. a ______ device can emit or detect light.

(a) light emitting diode (led)
(b) photonic
(c) piezoelectric crystal
(d) photovoltaic cell

Explanation:

1. Diodes convert AC to DC in vehicle chargers.
2. Zener diodes regulate voltage via reverse breakdown.
3. Voltage regulators stabilize circuit current/voltage.
4. BJTs use 3 layered semiconductor materials.
5. NPN uses P-type base, PNP uses N-type base; current flow direction differs.
6. Transistor A is PNP (arrow points in); Transistor B is NPN (arrow points out).
7. Both control signals; transistors are solid-state, relays use electromagnets.
8. Piezoelectric crystals generate current from pressure.
9. Photonic devices emit/detect light.

Answer:

1. diode
2. (D) Zener
3. voltage regulator
4. (B) three
5. The key difference is the type of semiconductor material used for the base: an NPN transistor has a P-type base sandwiched between two N-type layers, while a PNP transistor has an N-type base between two P-type layers. This reverses the direction of conventional current flow through the device (current flows into the collector of an NPN, and out of the collector of a PNP).
6. (A) PNP Transistor

(B) NPN Transistor

1. Similarities: Both transistors and relays act as switching/control devices to manage the flow of a larger signal using a smaller input signal.

Differences: Transistors are solid-state semiconductor devices with no moving parts, operate quickly, and are suitable for low-power, high-frequency applications. Relays are electromechanical devices with physical switches, handle higher power loads, but have slower response times and moving components that can wear out.

1. (C) piezoelectric crystal
2. (B) photonic