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# GROL

### GROL Element 3 A

Question | Answer |
---|---|

How does the input impedance of a field-effect transistor compare with that of a bipolar transistor? | An FET has high input impedance; a bipolar transistor has low input impedance. |

The product of the readings of an AC voltmeter and AC ammeter is called: | Apparent power. |

Good conductors with minimum resistance have what type of electrons? | Many free electrons. |

Permeability is defined as: | The ratio of magnetic flux density in a substance to the magnetizing force that produces it. |

How would you calculate the total capacitance of three capacitors in parallel? | CT = C1 + C2 + C3. |

When induced currents produce expanding magnetic fields around conductors in a direction that opposes the original magnetic field, this is known as: | Lenz’s law. |

How might you reduce the inductance of an antenna coil? | Reduce the number of turns. |

What limits the maximum forward current in a junction diode? | The junction temperature. |

An AC ammeter indicates: | Effective (RMS) values of current. |

By what factor must the voltage of an AC circuit, as indicated on the scale of an AC voltmeter, be multiplied to obtain the peak voltage value? | 1.414 |

Which of the following groups is correct for listing common materials in order of descending conductivity? | Silver, copper, aluminum, iron, and lead. |

What will produce a magnetic field? | A current flowing through a conductor. |

Halving the cross-sectional area of a conductor will: | Double the resistance. |

What is the relative dielectric constant for air? | 1 |

What are the two most commonly-used specifications for a junction diode? | Maximum forward current and PIV (peak inverse voltage). |

What type of wave is characterized by a rise time significantly faster than the fall time (or vice versa)? | Sawtooth wave. |

What is the description of a square wave? | A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amounts of time. |

Which of the 4 groups of metals listed below are the best low-resistance conductors? | Gold, silver, and copper. |

What formula would calculate the total inductance of inductors in series? | LT = L1 + L2 |

Skin effect is the phenomenon where: | RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases. |

What is the purpose of a bypass capacitor? | It removes alternating current by providing a low impedance path to ground. |

What is the peak voltage at a common household electrical outlet? | 165.5 volts. |

What type of wave is made up of sine waves of the fundamental frequency and all the odd harmonics? | Square. |

What is the term used to express the amount of electrical energy stored in an electrostatic field? | Joules |

What formula would determine the inductive reactance of a coil if frequency and coil inductance are known? | XL = 2πf L |

What are the two basic types of junction field-effect transistors? | N-channel and P-channel. |

What is the basic unit of electrical power? | Watt. |

What is the term used to identify an AC voltage that would cause the same heating in a resistor as a corresponding value of DC voltage? | Root mean square (RMS). |

Which of these will be most useful for insulation at UHF frequencies? | Mica. |

What device is used to store electrical energy in an electrostatic field? | Capacitor. |

What is the RMS voltage at a common household electrical power outlet? | 117-V AC. |

What type of wave is made up of sine waves at the fundamental frequency and all the harmonics? | Sawtooth wave. |

What determines the strength of the magnetic field around a conductor? | The amount of current. |

How do you compute true power (power dissipated in the circuit) in a circuit where AC voltage and current are out of phase? q | Multiply apparent power times the power factor. |

By what factor must the voltage measured in an AC circuit, as indicated on the scale of an AC voltmeter, be multiplied to obtain the average voltage value? | 0.9 |

What is a sine wave? | A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating at a uniform speed. |

MOSFETs are manufactured with THIS protective device built into their gate to protect the device from static charges and excessive voltages: | Zener diode. |

What happens to reactive power in a circuit that has both inductors and capacitors? | It alternates between magnetic and electric fields and is not dissipated. |

What is meant by the term “back EMF”? | A voltage that opposes the applied EMF. |

What is the term for the out-of-phase power associated with inductors and capacitors? | Reactive power. |

Which metal object may be least affected by galvanic corrosion when submerged in seawater? | Stainless steel propeller shaft. |

How many degrees are there in one complete sine wave cycle? | 360 degrees. |

What metal is usually employed as a sacrificial anode for corrosion control purposes? | Zinc bar. |

What is the easiest voltage amplitude to measure by viewing a pure sine wave signal on an oscilloscope? | Peak-to-peak. |

Assuming a power source to have a fixed value of internal resistance, maximum power will be transferred to the load when: | The load impedance equals the internal impedance of the source. |

The opposition to the creation of magnetic lines of force in a magnetic circuit is known as: | Reluctance. |

Corrosion resulting from electric current flow between dissimilar metals is called: | Galvanic corrosion. |

A common emitter amplifier has: | More voltage gain than a common collector. |