Technician T6D: Common circuits and parts
These are the 11 official questions in group T6D of the 2026–2030 Technician question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
- T6D01Question 1
Which of the following devices or circuits changes an alternating current into a varying direct current signal?
- ATransformer
- BRectifier Correct
- CAmplifier
- DReflector
Why: A rectifier turns AC into a varying DC signal.
- T6D02Question 2
What is a relay?
- AAn electrically-controlled switch Correct
- BA current-controlled amplifier
- CAn inverting amplifier
- DA pass transistor
Why: A relay is a switch operated by an electrical signal.
- T6D03Question 3
Which of the following is a reason to use shielded wire?
- ATo decrease the resistance of DC power connections
- BTo increase the current carrying capability of the wire
- CTo prevent coupling of unwanted signals to or from the wire Correct
- DTo reduce receiver overload
Why: Shielded wire keeps unwanted signals from coupling into or out of the wire.
- T6D04Question 4
Which of the following displays an electrical quantity as a numeric value?
- APotentiometer
- BTransistor
- CMeter Correct
- DRelay
Why: A meter shows an electrical quantity as a number.
- T6D05Question 5
What type of circuit controls the amount of voltage from a power supply?
- ARegulator Correct
- BOscillator
- CFilter
- DPhase inverter
Why: A regulator controls the output voltage of a power supply.
- T6D06Question 6
What component changes 120 V AC power to a lower AC voltage for other uses?
- AVariable capacitor
- BTransformer Correct
- CTransistor
- DDiode
Why: A transformer changes 120 V AC to a lower AC voltage.
- T6D07Question 7
Which of the following is commonly used as a visual indicator?
- ALED Correct
- BFET
- CZener diode
- DAll these choices are correct
Why: LEDs are commonly used as visual indicators.
- T6D08Question 8
Which of the following is combined with an inductor to make a resonant circuit?
- AResistor
- BZener diode
- CPotentiometer
- DCapacitor Correct
Why: A capacitor with an inductor makes a resonant circuit.
- T6D09Question 9
What is the name of a device that combines several semiconductors and other components into one package?
- ATransducer
- BMulti-pole relay
- CIntegrated circuit Correct
- DTransformer
Why: An integrated circuit combines many semiconductors and other parts in one package.
- T6D10Question 10
What is the function of component 2 in figure T-1?
- AGive off light when current flows through it
- BSupply electrical energy
- CControl the flow of current Correct
- DConvert electrical energy into radio waves
Why: The transistor (component 2) in T-1 controls the flow of current through the lamp.
- T6D11Question 11
Which of the following is a resonant or tuned circuit?
- AAn inductor and a capacitor in series or parallel Correct
- BA linear voltage regulator
- CA resistor circuit used for reducing standing wave ratio
- DA circuit designed to provide high-fidelity audio
Why: An inductor and capacitor in series or parallel form a resonant (tuned) circuit.