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2022 No Nonsense Technician Class License Study Guide - Electrical
Principles

Posted: 08 Jan 2022 12:00 PM PST https://www.kb6nu.com/2022-no-nonsense-technician-class-license-study-guide-electrical-principles/?utm_source=feedburner&utm_medium=email

Units and terms: current, voltage, and resistance; alternating and direct current; conductors and insulators

Figure 1 shows a simple electric circuit. It consists of a voltage source
(in this case a battery, labeled V), a resistor (labeled R), and some wires
to connect the battery to the resistor. When connected in this way, the
voltage across the battery will cause a current (labeled I) to flow through
the circuit. Voltage (V), current (I), and resistance (R) are the three
basic parameters of an electric circuit.
Figure 1. Simple electric circuit.

Voltage is the force that causes electrons to flow in a circuit. Voltage is measured in volts, and we use the letter V to represent both the force and
the units.
T5A05

What is the electrical term for the force that causes electron flow?

A. Voltage

B. Ampere-hours

C. Capacitance

D. Inductance

Current is the flow of electrons in a circuit. In Figure 1, the letter I
stands for current. Current flows from the positive (+) terminal of the
voltage source through the circuit to the negative terminal of the voltage source. Current is measured in amperes, and we use the letter A to stand
for amperes.
T5A03

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

A. Voltage

B. Resistance

C. Capacitance

D. Current
T5A01

Electrical current is measured in which of the following units?

A. Volts

B. Watts

C. Ohms

D. Amperes

Because the polarity of the battery voltage in the circuit never changes,
the current will flow in only one direction through the circuit. We call
this direct current, or DC. Batteries supply direct current, or simply, DC.

The type of current you get out of a wall socket is different from the
current that you get from a battery. We call it alternating current because
the voltage and current are constantly changing.
Figure 2. An alternating current (AC) waveform.

Figure 2 shows an alternating current waveform. That is to say it shows how
the voltage changes over time. For this particular waveform, the voltage
starts at 0 V, increases to a positive peak voltage, then decreases to a negative peak voltage, and then begins increasing again, until it once
again reaches 0 V. This process repeats over and over.
T5A09

Which of the following describes alternating current?

A. Current that alternates between a positive direction and zero

B. Current that alternates between a negative direction and zero

C. Current that alternates between positive and negative directions

D. All these answers are correct

One of the most important parameters of an alternating current is its frequency. The frequency of an alternating current is the number of times
per second that an alternating current makes a complete cycle, where a
cycle is the portion of an alternating current waveform that repeats over
and over. The frequency of the alternating current that you get from a wall socket in your home is 60 cycles per second, or in engineering terms, 60
hertz (Hz). 1 Hz is equal to one cycle per second.
T5A12

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

A. Pulse rate

B. Speed

C. Wavelength

D. Frequency
T5A06

What is the unit of frequency?

A. Hertz

B. Henry

C. Farad

D. Tesla

Resistance is the third basic parameter of an electric circuit. As the name implies, resistance opposes the flow of current in a circuit. The higher
the resistance, the smaller the current, for a given voltage. This applies
to direct current, alternating current, and RF current, which is
alternating current with a high frequency. We use the letter R to stand for resistance. Resistance is measured in ohms, and we use the Greek letter
omega (Ω) to stand for ohms.
T5A04

What are the units of electrical resistance?

A. Siemens

B. Mhos

C. Ohms

D. Coulombs
T5A11

What type of current flow is opposed by resistance?

A. Direct current

B. Alternating current

C. RF current

D. All these choices are correct

To connect components in an electric circuit, we generally use copper wires because they conduct electrical current well or, in other words, have a low resistance. Metals generally are good conductors because they have many
free electrons, and as a result offer low resistance to current flow.
T5A07

Why are metals generally good conductors of electricity?

A. They have relatively high density

B. They have many free electrons

C. They have many free protons

D. All these choices are correct

Silver is actually a better conductor than copper, but copper is a lot less expensive than silver. Often, you will see gold used as a conductor.
Although gold is not as good a conductor as either copper or silver, it doesn’t corrode like copper or silver. That makes it a good choice for
switch or connector contacts.

Many times we need a material that does not conduct current very well. We
call these materials insulators, and insulators have a high resistance. Plastics and glass are commonly used insulators.
T5A08

Which of the following is a good electrical insulator?

A. Copper

B. Glass

C. Aluminum

D. Mercury
Ohm’s Law: formulas and usage

Hams obey Ohm’s Law!

Ohm’s Law is the relationship between voltage, current, and resistance in
an electrical circuit. When you know any two of these values, you can
calculate the third.

The most basic equation for Ohm’s Law is V = I × R. In other words, when
you know the current (I) flowing through a circuit and the resistance (R)
of the circuit, you can calculate the voltage across the circuit by
multiplying these two values.
T5D02

What formula is used to calculate voltage in a circuit?

A. V = I x R

B. V = I / R

C. V = I + R

D. V = I R

Using simple algebra, you can derive the other two forms of this equation:
R = V / I and I = V / R. These two equations let you calculate the
resistance in a circuit if you know the voltage and current or the current
in a circuit if you know the voltage and resistance.
T5D03

What formula is used to calculate resistance in a circuit?

A. R = V x I

B. R = V / I

C. R = V + I

D. R = V – I
T5D01

What formula is used to calculate current in a circuit?

A. I = V x R

B. I = V / R

C. I = V + R

D. I = V R

Now, let’s look at some examples of how to apply Ohm’s Law.
T5D04

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

A. 3 ohms

B. 30 ohms

C. 93 ohms

D. 270 ohms

Here’s how to calculate this answer: R = V / I = 90 V / 3 A = 30 Ω
T5D05

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

A. 18 ohms

B. 0.125 ohms

C. 8 ohms

D. 13.5 ohms

R = V / I = 12 V / 1.5 A = 8 Ω
T5D06

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

A. 3 ohms

B. 16 ohms

C. 48 ohms

D. 8 ohms

R = V / I = 12 V / 4 A = 3 Ω.

Now, lets look at another form of the Ohms Law equation, I = V / R to
calculate the current in a circuit.
T5D07

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

A. 9600 amperes

B. 200 amperes

C. 0.667 amperes

D. 1.5 amperes

I = V / R = 120 V / 80 Ω = 1.5 A
T5D08

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

A. 20,000 amperes

B. 0.5 amperes

C. 2 amperes

D. 100 amperes

I = V / R = 200 V / 100 Ω = 2 A
T5D09

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

A. 24,000 amperes

B. 0.1 amperes

C. 10 amperes

D. 216 amperes

I = V / R = 240 V / 24 Ω = 10 A

Now, lets look at the third form of the Ohms Law equation, E = I × R to calculate the voltage across a circuit.
T5D10

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

A. 1 volt

B. 0.25 volts

C. 2.5 volts

D. 1.5 volts

V = I × R = 0.5 A × 2 Ω = 1 V
T5D11

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

A. 1 volt

B. 10 volts

C. 11 volts

D. 9 volts

V = I × R = 1 A × 10 Ω = 10 V
T5D12

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

A. 8 volts

B. 0.2 volts

C. 12 volts

D. 20 volts

V = I × R = 2 A × 10 Ω = 20 V
Series and parallel circuits

Now, let’s consider circuits with two resistors instead of just a single resistor. There are two ways in which the two resistors can be connected:
in series or in parallel. Figure 3 shows a series circuit.
Figure 3. Series circuit.

There is only one path for the current to flow, so the same current flows through both resistors. If R1 = R2, then the voltage will be the same
across both resistors, because the same current flows through both
resistors. If R1 does not equal R2, however, the voltages will be
different. In either case, the sum of the two voltages will equal the
voltage of the voltage source.
T5D13

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

A. Series

B. Parallel

C. Resonant

D. Branch

In a parallel circuit, shown in Figure 4, both resistors are connected
directly to the voltage source.
Figure 4. Parallel circuit

Because both components are connected directly to the voltage source, the voltage across them will be the same. This voltage will cause currents to
flow in each of the resistors. I1 = V/R1, and I2 = V/R2. The total current,
I, is equal to I1 + I2. If R1 = R2, then the same current flows through
both resistors. If the resistors have different values, then I1 will be different from I2.
T5D14

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

A. Series

B. Parallel

C. Resonant

D. Branch
DC power

Power is the rate at which electrical energy is generated or consumed.
Power is measured in watts. We use the letter P to stand for power and the letter W to stand for watts.
T5A10

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

A. Resistance

B. Current

C. Power

D. Voltage
T5A02

Electrical power is measured in which of the following units?

A. Volts

B. Watts

C. Watt-hours

D. Amperes

To calculate power, we multiply the voltage across a circuit by the current flowing through the circuit. We write this equation P = V × I.
T5C08

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

A. P = V x I

B. P = V / I

C. P = V – I

D. P = V + I

Here are some examples:
T5C09

How much power is delivered by a voltage of 13.8 volts DC and a current of
10 amperes?

A. 138 watts

B. 0.7 watts

C. 23.8 watts

D. 3.8 watts

The calculation for this question is P = V × I = 13.8 V × 10 A = 138 W.
T5C10

How much power is delivered by a voltage of 12 volts DC and a current of
2.5 amperes?

A. 4.8 watts

B. 30 watts

C. 14.5 watts

D. 0.208 watts

The calculation for this question is P = V × I = 12 V × 2.5 A = 30 W.

Just as with Ohm’s Law, you can use algebra to come up with other forms of this equation to calculate the voltage if you know the power and the
current, or to calculate the current if you know the power and the voltage.
The formula to calculate the current, if you know the power and the
voltage, is I = P / V.
T5C11

How much current is required to deliver 120 watts at a voltage of 12 volts
DC?

A. 0.1 amperes

B. 10 amperes

C. 12 amperes

D. 132 amperes

The calculation for this question is I = P / V = 120 W / 12 V = 10 A.
Math for electronics and conversion of electrical units

When dealing with electrical parameters such as voltage, resistance,
current, and power, we use a set of prefixes to denote various orders of magnitude:

milli- is the prefix used to denote 1 one-thousandth of a quantity. A milliampere, for example, is 1 one-thousandth of an ampere, or 0.001 A.
Often, the letter m is used instead of the prefix milli-. 1 milliampere is, therefore, 1 mA.
micro- is the prefix used to denote 1 one-millionth of a quantity. A
microvolt, for example, is 1 one-millionth of a volt, or 0.000001 V. Often,
you will see the Greek letter mu, or μ, used to denote the prefix micro-. 1 microvolt is, therefore, 1 μV.
pico- is the prefix used to denote 1 one-trillionth of a quantity. A
picovolt is 1 one-trillionth of a volt, or 0.000001 μV.
kilo- is the prefix used to denote 1 thousand of a quantity. A kilovolt,
for example, is 1000 volts. Often, the letter k is used instead of the
prefix kilo-. 1 kilovolt is, therefore, 1 kV.
mega- is the prefix used to denote 1 million of a quantity. A megahertz,
for example, is 1 million Hertz. Often, the letter M is used instead of the prefix mega-. 1 megahertz is, therefore, 1 MHz.
giga is the prefix used to denote one billion of a quantity. One
gigahertz, or 1 GHz, for example is 1 billion Hertz.




Prefix
Abbreviation
Numerical
Exponential


giga-
G
1,000,000,000
109


mega-
M
1,000,000
106


kilo-
k
1,000
103


-
-
1
100


milli-
m
0.001
10-3


micro-
μ,u
0.000001
10-6


nano-
n
0.000000001
10-9


pico-
p
0.000000000001
10-12




Here are some examples:
T5B01

How many milliamperes is 1.5 amperes?

A. 15 milliamperes

B. 150 milliamperes

C. 1500 milliamperes

D. 15,000 milliamperes

To convert amperes to milliamperes, you multiply by 1,000.
T5B02

Which is equal to 1,500,000 hertz?

A. 1500 kHz

B. 1500 MHz

C. 15 GHz

D. 150 kHz

To convert from hertz (Hz) to kHz, you divide by 1,000.
T5B03

Which is equal to one kilovolt?

A. One one-thousandth of a volt

B. One hundred volts

C. One thousand volts

D. One million volts
T5B04

Which is equal to one microvolt?

A. One one-millionth of a volt

B. One million volts

C. One thousand kilovolts

D. One one-thousandth of a volt

To convert from kilovolts to volts, you multiply by 1,000. To convert from microvolts to volts, you divide by one million.
T5B05

Which is equal to 500 milliwatts?

A. 0.02 watts

B. 0.5 watts

C. 5 watts

D. 50 watts

To convert from milliwatts to watts, you divide by 1,000. 500 / 1000 = ½ or 0.5.
T5B08

Which is equal to 1,000,000 picofarads?

A. 0.001 microfarads

B. 1 microfarad

C. 1000 microfarads

D. 1,000,000,000 microfarad

The farad is the unit of capacitance. There are 1 million picofarads in a microfarad.
T5B06

Which is equal to 3000 milliamperes?

A. 0.003 amperes

B. 0.3 amperes

C. 3,000,000 amperes

D. 3 amperes

There are a thousand milliamperes in an ampere, so to convert from
milliamperes to amperes, you divide by 1,000.
T5C13

What is the abbreviation for kilohertz?

A. KHZ

B. khz

C. khZ

D. kHz

1 kHz is 1,000 Hz or 1,000 cycles per second. Note that the “H” in Hz is capitalized.
T5B07

Which is equal to 3.525 MHz?

A. 0.003525 kHz

B. 35.25 kHz

C. 3525 kHz

D. 3,525,000 kHz
T5B12

Which is equal to 28400 kHz?

A. 28.400 kHz

B. 2.800 MHz

C. 284.00 MHz

D. 28.400 MHz
T5B13

Which is equal to 2425 MHz?

A. 0.002425 GHz

B. 24.25 GHz

C. 2.425 GHz

D. 2425 GHz

To convert from MHz to kHz, you multiply by 1,000. To convert from kHz to
MHz, or to convert from MHz to GHz, you divide by 1,000.
Decibels

When dealing with ratios—especially power ratios—we often use decibels (dB). The reason for this is that the decibel scale is a logarithmic scale, meaning that we can talk about large ratios with relatively small numbers.
When the value is positive, it means that there is a power increase. When
the value is negative, it means that there is a power decrease.

At this point, you don’t need to know the formula used to calculate the
ratio in dB, but you need to know the ratios represented by the values 3
dB, 6 dB, and 10 dB.
T5B09

Which decibel value most closely represents a power increase from 5 watts
to 10 watts?

A. 2 dB

B. 3 dB

C. 5 dB

D. 10 dB

3 dB corresponds to a ratio of 2 to 1, and because going from 5 watts to 10 watts doubles the power, we can also say that there is a gain of 3 dB.
T5B10

Which decibel value most closely represents a power decrease from 12 watts
to 3 watts?

A. -1 dB

B. -3 dB

C. -6 dB

D. -9 dB

6 dB corresponds to a ratio of 4 to 1, and a decrease in power from 12
watts to 3 watts is a ratio of 4 to 1. Because this is a power decrease,
the value in dB is negative.
T5B11

Which decibel value represents a power increase from 20 watts to 200 watts?

A. 10 dB

B. 12 dB

C. 18 dB

D. 28 dB

Increasing the power from 20 watts to 200 watts is a ratio of 10 to 1, and
10 dB corresponds to a ratio of 10 to 1.

The post 2022 No Nonsense Technician Class License Study Guide Electrical Principles appeared first on KB6NUs Ham Radio Blog.


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NCVEC makes big changes to Tech question pool

Posted: 08 Jan 2022 12:00 PM PST https://www.kb6nu.com/ncvec-makes-big-changes-to-tech-question-pool/?utm_source=feedburner&utm_medium=email


The 2022 version of the Technician Class question pool is out. The National Council of Voluteer Examiner Coordinators have really made quite a few
changes to the question pool this time. They removed 64 questions, added 51
new questions, and updated 136 questions. There are now a total of 412 questions total. This means that close to half of the questions are
different from the last question pool.

I got started working on updating my No Nonsense Technician Class License
Study Guide this week. From the get go, I ran into questions that had been deleted or modified. T5A05 is the first question that I cover in the study guide. The question in 2018 question pool reads:
What is the electrical term for the electromotive force (EMF) that causes electron flow?

(ANSWER: Voltage)

This question is followed by:
What is the unit of electromotive force?

(ANSWER: The volt)

Now, T5A05 reads:
What is the electrical term for the force that causes electron flow?

(ASNWER: Voltage)

The second question about the unit of electromotive force has been deleted.

Im not really sure that either version of the question is 100% correct, but after consulting with my friend Bob Witte, K0NR, and Ward Silver, N0AX
(editor of the ARRL Handbook), Ive decided to just let it go. They point
out that even authors of engineering textbooks are split on how to describe
the relationship of electromove force and voltage.

The ARRL Handbook 2022 is kind of equivocal:
Electromotive force (or EMF) [is] the source of energy that causes charged particles to move. Voltage is the general term for the strength of the electromotive force or the different in electrical potential between two points. Voltage and EMF  are often used interchangeably in radio.

Ill also note that they use EMF and the letter E when they define Ohms Law
and describe Kirchoffs Voltage Law.

Speaking of equations, since the Question Pool committee has decided to go
with voltage instead of EMF, they had to change all of the questions
dealing with Ohms Law a power calculation. For example, the answer to
T5D02, What formula is used to calculate voltage in a circuit? was Voltage
(E) equals current (I) multiplied by resistance (R) in the 2018 question
pool, but is now simply V = I x R. The questions dealing with the other versions of Ohms Law have been similarly changed.

Despite this, I do think this version of the question pool has been
improved. Theyve eliminated, for example T5A06, How much voltage does a
mobile transceiver typically require? This question wasnt so bad in and of itself, but it just didnt belong in this section. They also improved the question about electrical conductors. Instead of just asking which material
is a good conductor, they now ask, Why are metals generally good conductors
of electricity?

At any rate, Im now hard at work on updating the study guide. I have, in
fact, already completed the first draft of the first chapter. Click here to take a look at it. Let me know what you think.

The post NCVEC makes big changes to Tech question pool appeared first on
KB6NUs Ham Radio Blog.


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Want to learn antenna modeling? EZNEC is now free!

Posted: 07 Jan 2022 10:39 AM PST https://www.kb6nu.com/want-to-learn-antenna-modeling-eznec-is-now-free/?utm_source=feedburner&utm_medium=email

EZNEC, the popular antenna-modeling software by Roy, W7EL, is now FREE!

This might be a good time to learn antenna modeling. EZNEC, the very
popular antenna-modeling software written by Roy Lewallen, W7EL, is now
FREE! The EZNEC website notes:

EZNEC IS NO LONGER FOR SALE. IT IS FREE (see below)
THERE WILL BE NO SUPPORT OR REFUNDS

The introduction of EZNEC Pro/2+ v. 7.0 has been unavoidably delayed. The estimated time of introduction is Jan. 14, 2022, but Ill do my very best to have it ready before then. It is now undergoing extensive testing and
updating of the manual.

EZNEC Pro/2+ v. 7.0 will have all the features of EZNEC Pro/2 v. 6.0, plus extra features including wire loss for individual wires and the ability to
run external NEC-4.2 and NEC-5 programs for calculation.

Until EZNEC Pro/2+ v. 7.0 is available, you can download EZNEC Pro/2 v. 6.0
by clicking here:

Download EZNEC Pro/2 v. 6.0

Roy also notes:

I want to thank the many people who have sent encouraging and complimentary messages about my retirement. Im very sorry I havent been able to respond because my time has been intensely taken up in getting the new EZNEC Pro+ programs ready. Ill attempt to respond individually after the programs have been released.

Watch this page for the EZNEC Pro/2+ and EZNEC Pro/4+ announcement and
other updates!

A fellow on Reddit writes, For those of you that have never modeled before,
I highly recommend reading the four part introduction to antenna modeling written by L. B. Cebik (W4RNL). It appeared in QST a number of years ago
and is available on the ARRL web site.

http://www.arrl.org/antenna-modeling. Also, the help file for EZNEC
contains a decent tutorial as well.

The post Want to learn antenna modeling? EZNEC is now free! appeared first
on KB6NUs Ham Radio Blog.

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