Ham Radio Technician Test Basic Electronics & Circuitry 4 — Questions and Answers
Question 1: What is the effect of adding a capacitor in series with an antenna feedline for DC blocking?
- It amplifies the RF signal
- It passes RF while blocking DC (Correct answer)
- It blocks RF while passing DC
- It increases the antenna's resonant frequency
Correct answer: It passes RF while blocking DC
A series capacitor blocks DC but presents low impedance to RF signals, allowing them to pass.
Question 2: What is the power factor of a purely resistive AC circuit?
- 0
- 0.5
- 1 (Correct answer)
- Infinity
Correct answer: 1
A purely resistive circuit has a power factor of 1 because voltage and current are in phase.
Question 3: Which semiconductor device is commonly used as a voltage-controlled switch in digital logic?
- Zener diode
- MOSFET (Correct answer)
- Varactor diode
- SCR
Correct answer: MOSFET
MOSFETs are widely used as switches in digital logic because gate voltage controls channel conductivity.
Question 4: What is the purpose of a decoupling capacitor placed near an IC power pin?
- Increase the supply voltage to the IC
- Filter high-frequency noise and supply instantaneous current (Correct answer)
- Reduce the clock speed of the IC
- Convert AC supply to DC for the IC
Correct answer: Filter high-frequency noise and supply instantaneous current
Decoupling capacitors filter power supply noise and provide local charge reservoir for fast current demands.
Question 5: What does the 'Q' factor of a coil or resonant circuit indicate?
- The charge stored in coulombs
- The ratio of reactance to resistance, indicating selectivity and efficiency (Correct answer)
- The number of turns in the coil
- The maximum current the coil can carry
Correct answer: The ratio of reactance to resistance, indicating selectivity and efficiency
Q factor is the ratio of reactance to resistance; higher Q means sharper resonance and lower losses.
Question 6: In which region does a transistor operate when used as a linear amplifier?
- Saturation region
- Cutoff region
- Active (linear) region (Correct answer)
- Breakdown region
Correct answer: Active (linear) region
Linear amplifiers operate transistors in the active region where collector current varies proportionally with base current.
Question 7: What is electrical impedance?
- Resistance to DC current only
- The total opposition to AC current including resistance and reactance (Correct answer)
- The power dissipated in a circuit
- The ratio of current to voltage
Correct answer: The total opposition to AC current including resistance and reactance
Impedance (Z) combines resistance and reactance into the total opposition to AC current flow.
Ham Radio Technician Test Basic Electronics & Circuitry 4
What is the effect of adding a capacitor in series with an antenna feedline for DC blocking?