W4CA

Roanoke Valley Amateur Radio Club

T-5

Read Cliff Notes

Download

Watch PowerPoint

Download

Read Right Answers Only

SUBELEMENT T5

Electrical principles: math; electronic principles; Ohm’s Law

[4 Exam Questions – 4 Groups]

 

Electrical current is measured in which of the following units?

  1. Amperes

Electrical power is measured in which of the following units?

  1. Watts

What is the name for the flow of electrons in an electric circuit?

  1. Current

What is the name for a current that flows only in one direction?

  1. Direct current

What is the electrical term for the electromotive force (EMF) that causes electron flow?

  1. Voltage

How much voltage does a mobile transceiver typically require?

  1. About 12 volts

Which of the following is a good electrical conductor?

  1. Copper

Which of the following is a good electrical insulator?

  1. Glass

What is the name for a current that reverses direction on a regular basis?

  1. Alternating current

Which term describes the rate at which electrical energy is used?

  1. Power

What is the unit of electromotive force?

  1. The volt

What describes the number of times per second that an alternating current makes a complete cycle?

  1. Frequency

In which type of circuit is current the same through all components?

  1. Series

In which type of circuit is voltage the same across all components?

  1. Parallel

How many milliamperes is 1.5 amperes?

  1. 1500 milliamperes

What is another way to specify a radio signal frequency of 1,500,000 hertz?

  1. 1500 kHz

How many volts are equal to one kilovolt?

  1. One thousand volts

How many volts are equal to one microvolt?

  1. One one-millionth of a volt

Which of the following is equal to 500 milliwatts?

  1. 0.5 watts

If an ammeter calibrated in amperes is used to measure a 3000-milliampere current, what reading would it show?

  1. 3 amperes

If a frequency display calibrated in megahertz shows a reading of 3.525 MHz, what would it show if it were calibrated in kilohertz?

  1. 3525 kHz

How many microfarads are equal to 1,000,000 picofarads?

  1. 1 microfarad

What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts?

  1. 3 dB

What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts?

  1. -6 dB

What is the amount of change, measured in decibels (dB), of a power increase from 20 watts to 200 watts?

  1. 10 dB

Which of the following frequencies is equal to 28,400 kHz?

  1. 28.400 MHz

If a frequency display shows a reading of 2425 MHz, what frequency is that in GHz?

  1. 2.425 GHz

What is the ability to store energy in an electric field called?

  1. Capacitance

What is the basic unit of capacitance?

  1. The farad

What is the ability to store energy in a magnetic field called?

  1. Inductance

What is the basic unit of inductance?

  1. The henry

What is the unit of frequency?

  1. Hertz

What does the abbreviation “RF” refer to?

  1. Radio frequency signals of all types

A radio wave is made up of what type of energy?

  1. Electromagnetic

What is the formula used to calculate electrical power in a DC circuit?

  1. Power (P) equals voltage (E) multiplied by current (I)

How much power is being used in a circuit when the applied voltage is 13.8 volts DC and the current is 10 amperes?

  1. 138 watts

How much power is being used in a circuit when the applied voltage is 12 volts DC and the current is 2.5 amperes?

  1. 30 watts

How many amperes are flowing in a circuit when the applied voltage is 12 volts DC and the load is 120 watts?

  1. 10 amperes

What is impedance?

  1. A measure of the opposition to AC current flow in a circuit

What are the units of impedance?

  1. Ohms

What is the proper abbreviation for megahertz?
D. MHz

What formula is used to calculate current in a circuit?

  1. Current (I) equals voltage (E) divided by resistance (R)

What formula is used to calculate voltage in a circuit?

  1. Voltage (E) equals current (I) multiplied by resistance (R)

What formula is used to calculate resistance in a circuit?

  1. Resistance (R) equals voltage (E) divided by current (I)

What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts?

  1. 30 ohms

What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes?

  1. 8 ohms

 

What is the resistance of a circuit that draws 4 amperes from a 12-volt source?

  1. 3 ohms

What is the current in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?

  1. 1.5 amperes

What is the current through a 100-ohm resistor connected across 200 volts?

  1. 2 amperes

What is the current through a 24-ohm resistor connected across 240 volts?

  1. 10 amperes

What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?

  1. 1 volt

What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?

  1. 10 volts

What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it?

  1. 20 volts

What happens to current at the junction of two components in series?

  1. It is unchanged

What happens to current at the junction of two components in parallel?

  1. It divides between them dependent on the value of the components

T5D15 (C)

What is the voltage across each of two components in series with a voltage source?

  1. It is determined by the type and value of the components

What is the voltage across each of two components in parallel with a voltage source?

  1. The same voltage as the source

 

Go to ARRL Exam Review

Sign IN

Review for Exam

General Review

Review by Subelement

Select Groups from Individual Subelements

Select ALL

Check % on the Right Side

LOOKING for 85% or BETTER

Use the Left Arrow Key

ARRL Exam Review

Go to T-3