GROL Semiconductor and Tube Components 2

Question 1

What is the primary purpose of the screen grid in a tetrode vacuum tube?

Accepted Answer

To reduce interelectrode capacitance between control grid and plate

Answer

To emit secondary electrons toward the collector

Answer

To regulate the cathode emission current

Answer

To provide a reference voltage for the control grid

Question 2

The amplification factor (μ) of a vacuum tube is defined as:

Accepted Answer

The magnitude of plate voltage change per unit grid voltage change needed to keep plate current constant

Answer

The ratio of transconductance to plate resistance

Answer

The ratio of plate current change to control grid voltage change

Answer

The ratio of plate resistance to transconductance

Question 3

In an NPN bipolar junction transistor operating in the active (linear) region, the junction biasing is:

Accepted Answer

Emitter-base junction forward biased and collector-base junction reverse biased

Answer

Both emitter-base and collector-base junctions reverse biased

Answer

Both emitter-base and collector-base junctions forward biased

Answer

Emitter-base junction reverse biased and collector-base junction forward biased

Question 4

The DC current gain parameter hFE of a BJT is defined as the ratio of:

Accepted Answer

Collector current to base current

Answer

Emitter current to base current

Answer

Emitter current to collector current

Answer

Base current to emitter current

Question 5

A reflex klystron differs from a two-cavity klystron in that it uses:

Accepted Answer

A single resonant cavity with a repeller electrode that returns velocity-modulated electrons for a second pass through the gap

Answer

A traveling-wave helix to slow the RF signal

Answer

A magnetron cavity for broadband resonance

Answer

Multiple drift tubes for staged velocity modulation

Question 6

The suppressor grid of a pentode vacuum tube is held at cathode potential in order to:

Accepted Answer

Repel secondary electrons emitted from the plate back to the plate rather than allowing them to reach the screen grid

Answer

Accelerate secondary electrons from the plate toward the screen grid

Answer

Provide a fixed negative bias that reduces overall plate current

Answer

Shield the control grid from variations in plate voltage

Question 7

A common-emitter BJT amplifier stage produces an output voltage signal that is:

Accepted Answer

180° out of phase with the input signal (inverted)

Answer

In phase with the input signal (0° phase shift)

Answer

90° out of phase with the input signal

Answer

45° out of phase with the input signal