Canadian (from VE2AAY) Basic Qualification pool, section L02

Subelement L02

Basics Electricity.

Section L02

B-3-16-1

How much voltage does a standard automobile battery usually supply?

A.
About 120 volts
B.
About 9 volts
Correct Answer
C.
About 12 volts
D.
About 240 volts

B-3-16-1

Also known as a 'storage cell', the common Lead-Acid battery has a nominal voltage of 12 volts [ 12.6 to be exact ]

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B-3-16-2

Which component has a positive and a negative side?

Correct Answer
A.
A battery
B.
A potentiometer
C.
A fuse
D.
A resistor

B-3-16-2

Fuses, resistors and potentiometers are not 'polarized' (current can flow through them either way). The battery, however, has a positive terminal and a negative terminal.

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B-3-16-3

A cell, that can be repeatedly recharged by supplying it with electrical energy, is known as a:

A.
low leakage cell
B.
memory cell
C.
primary cell
Correct Answer
D.
storage cell

B-3-16-3

A 'storage cell' can be recharged repeatedly. A 'primary cell', such as a common Zinc-Carbon flashlight cell, can only be used once.

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B-3-16-4

Which of the following is a source of electromotive force (EMF)?

A.
carbon resistor
Correct Answer
B.
lithium-ion battery
C.
germanium diode
D.
P channel FET

B-3-16-4

EMF = Electromotive Force, synonym for voltage. Lithium-ion batteries are common in modern portable equipment.

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B-3-16-5

An important difference between a conventional flashlight battery and a lead acid battery is that only the lead acid battery:

A.
has two terminals
B.
can be completely discharged
C.
contains an electrolyte
Correct Answer
D.
can be repeatedly recharged

B-3-16-5

The 'conventional' Zinc-Carbon or Alkaline flashlight battery CANNOT be recharged while a 'storage cell' like a car battery can be recharged numerous times.

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B-3-16-6

An alkaline cell has a nominal voltage of 1.5 volts. When supplying a great deal of current, the voltage may drop to 1.2 volts. This is caused by the cell's:

A.
voltage capacity
Correct Answer
B.
internal resistance
C.
electrolyte becoming dry
D.
current capacity

B-3-16-6

An ideal battery would supply precisely the same voltage regardless of the current drawn. Real-life batteries exhibit 'internal resistance' which causes a drop in voltage when current is drawn. Ever noticed the headlights dim when the starter is cranked on a cold winter day ?

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B-3-16-7

An inexpensive primary cell in use today is the carbon-zinc or flashlight cell. This type of cell can be recharged:

Correct Answer
A.
never
B.
twice
C.
many times
D.
once

B-3-16-7

The 'conventional' Zinc-Carbon or Alkaline flashlight battery CANNOT be recharged while a 'storage cell' like a car battery can be recharged numerous times.

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B-3-16-8

Battery capacity is commonly stated as a value of current delivered over a specified period of time. What is the effect of exceeding that specified current?

A.
The battery will accept the subsequent charge in shorter time
B.
The voltage delivered will be higher
Correct Answer
C.
A battery charge will not last as long
D.
The internal resistance of the cell is short-circuited

B-3-16-8

One important specification of rechargeable batteries is the 'capacity' expressed in milliampere-hour (or ampere-hour), a certain amount of current that can be delivered for a given period of time (typically, 20 hours). Exceeding the capacity reduces operating time, the battery is depleted more rapidly.

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B-3-16-9

To increase the current capacity of a cell, several cells should be connected in:

Correct Answer
A.
parallel
B.
series
C.
parallel resonant
D.
series resonant

B-3-16-9

key word: CURRENT. A parallel combination of batteries will permit supplying more current at a given voltage.

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B-3-16-10

To increase the voltage output, several cells are connected in:

A.
parallel
B.
series-parallel
C.
resonance
Correct Answer
D.
series

B-3-16-10

key word: VOLTAGE. Adding cells in series brings up the available voltage. However, the total current available from the string remains limited to what a single cell can supply.

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B-3-16-11

A lithium-ion battery should never be:

A.
left disconnected
B.
left overnight at room temperature
Correct Answer
C.
short-circuited
D.
recharged

B-3-16-11

Lithium-ion cells have very low 'internal resistance'. Hence, they can supply potentially dangerous currents in a short-circuit.

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B-4-6-1

How do you find a resistor's tolerance rating?

A.
By using Thevenin's theorem for resistors
B.
By reading its Baudot code
C.
By using a voltmeter
Correct Answer
D.
By reading the resistor's colour code

B-4-6-1

The last band in a resistor's colour code identifies 'tolerance': an allowed variance in percentage from the nominal value. For example, a GOLD band means 5%.

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B-4-6-2

What do the first three-colour bands on a resistor indicate?

A.
The resistance material
B.
The power rating in watts
C.
The resistance tolerance in percent
Correct Answer
D.
The value of the resistor in ohms

B-4-6-2

The first two bands are significant digits, the third band is a multiplier. The fourth band is tolerance.

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B-4-6-3

What would the fourth colour band on a 47 ohm resistor indicate?

Correct Answer
A.
The resistance tolerance in percent
B.
The value of the resistor in ohms
C.
The power rating in watts
D.
The resistance material

B-4-6-3

The last band in a resistor's colour code identifies 'tolerance': an allowed variance in percentage from the nominal value. For example, a GOLD band means 5%.

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B-4-6-4

What are the possible values of a 100 ohm resistor with a 10% tolerance?

Correct Answer
A.
90 to 110 ohms
B.
90 to 100 ohms
C.
10 to 100 ohms
D.
80 to 120 ohms

B-4-6-4

100 ohms minus 10% is 90 ohms, 100 ohms plus 10 % is 110 ohms.

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B-4-6-5

How do you find a resistor's value?

A.
By using the Baudot code
Correct Answer
B.
By using the resistor's colour code
C.
By using a voltmeter
D.
By using Thevenin's theorem for resistors

B-4-6-5

The first two bands are significant digits, the third band is a multiplier. The last band is tolerance.

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B-4-6-6

A club project requires that a resistive voltage divider provide a very accurate and predictable ratio. Out of the list below, which resistor tolerance would you select?

A.
10%
B.
20%
Correct Answer
C.
0.1%
D.
5%

B-4-6-6

Key words: ACCURATE and PREDICTABLE. The smallest possible "tolerance" will ensure that the actual value of the resistors fall within a narrow range of their nominal values.

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B-4-6-7

You need a current limiting resistor for a light-emitting diode (LED). The actual resistance is not critical at all. Out of the list below, which resistor tolerance would you select?

A.
10%
Correct Answer
B.
20%
C.
0.1%
D.
5%

B-4-6-7

Key words: NOT CRITICAL. A wide tolerance is amply acceptable when the actual value of the resistor is not critical. The extra cost of a precision resistor is not needed.

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B-4-6-8

If a carbon resistor's temperature is increased, what will happen to the resistance?

A.
It will stay the same
B.
It will become time dependent
C.
It will increase by 20% for every 10 degrees centigrade
Correct Answer
D.
It will change depending on the resistor's temperature coefficient rating

B-4-6-8

Temperature affects all components and conductors.

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B-4-6-9

A gold tolerance band on a resistor indicates the tolerance is:

A.
10%
B.
1%
Correct Answer
C.
5%
D.
20%

B-4-6-9

'Gold' means 5%.

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B-4-6-10

Which colour band would differentiate a 120-ohm from a 1200-ohm resistor?

A.
Second band
B.
Fourth band
Correct Answer
C.
Third band
D.
First band

B-4-6-10

The first two bands are significant digits, the third band is a multiplier. The fourth band is tolerance. In this example, both first bands read '1', both second bands read '2'. The third band multiplies by 10 or 100 as the case may be.

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B-4-6-11

Given that red=2, violet=7 and yellow=4, what is the nominal value of a resistor whose colour code reads "red", "violet" and "yellow"?

Correct Answer
A.
270 kilohms
B.
274 ohms
C.
72 kilohms
D.
27 megohms

B-4-6-11

The first two bands are significant digits, the third band is a multiplier. The fourth band is tolerance. In this example, the first two digits are '27' and the multiplier adds four zeroes (or multiplies by 10 000). Result = 270 000 ohms or 270 kilohms.

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B-5-1-2

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

A.
3 000 000 amperes
Correct Answer
B.
3 amperes
C.
0.003 ampere
D.
0.3 ampere

B-5-1-2

Milli is a thousandth. A thousand milliamperes is one ampere. Converting from milliamperes to amperes: from small units to larger units, requires fewer digits, decimal point moves to the left by three positions, a thousand times less.

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B-5-1-3

If a voltmeter marked in volts is used to measure a 3500 millivolt potential, what reading would it show?

Correct Answer
A.
3.5 volts
B.
0.35 volt
C.
35 volts
D.
350 volts

B-5-1-3

Milli is a thousandth. A thousand millivolts is one volt. Converting from millivolts to volts: from small units to larger units, requires fewer digits, decimal point moves to the left by three positions, a thousand times less.

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B-5-1-6

A kilohm is:

A.
0.1 ohm
B.
0.001 ohm
C.
10 ohms
Correct Answer
D.
1000 ohms

B-5-1-6

Kilohm is a thousand ohms. Converting from kilohm to ohms: from large units to smaller units, requires more digits, decimal point moves to the right by three positions, a thousand times more.

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B-5-1-7

6.6 kilovolts is equal to:

A.
660 volts
B.
66 volts
C.
66 000 volts
Correct Answer
D.
6600 volts

B-5-1-7

Kilovolt is a thousand volts. Converting from kilovolts to volts: from large units to smaller units, requires more digits, decimal point moves to the right by three positions, a thousand times more.

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B-5-1-8

A current of one quarter ampere may be written as:

A.
0.25 milliampere
B.
250 microamperes
Correct Answer
C.
250 milliamperes
D.
0.5 amperes

B-5-1-8

One quarter ampere is 0.25 amperes. Milli is one thousandth. One ampere is a thousand milliamperes. Converting from ampere to milliampere: from large units to smaller units, requires more digits, decimal point moves to the right by three positions, a thousand times more.

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B-5-1-9

How many millivolts are equivalent to two volts?

A.
0.002
Correct Answer
B.
2 000
C.
0.000002
D.
2 000 000

B-5-1-9

A millivolt is a thousandth of a volt. A volt is one thousand millivolts. Converting from volts to millivolts: from large units to smaller units, requires more digits, decimal point moves to the right by three positions, a thousand times more.

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B-5-2-1

Name three good electrical conductors.

A.
Copper, aluminum, paper
B.
Copper, gold, mica
Correct Answer
C.
Gold, silver, aluminum
D.
Gold, silver, wood

B-5-2-1

Wood, paper and mica do NOT conduct electricity. The best conductors, in descending order, are: Silver, Copper, Gold and Aluminum.

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B-5-2-2

Name four good electrical insulators.

A.
Plastic, rubber, wood, carbon
B.
Paper, glass, air, aluminum
C.
Glass, wood, copper, porcelain
Correct Answer
D.
Glass, air, plastic, porcelain

B-5-2-2

Copper and aluminum are CONDUCTORS. Carbon is a poor conductor, it is used to fabricate resistors.

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B-5-2-3

Why do resistors sometimes get hot when in use?

Correct Answer
A.
Some electrical energy passing through them is lost as heat
B.
Their reactance makes them heat up
C.
Hotter circuit components nearby heat them up
D.
They absorb magnetic energy which makes them hot

B-5-2-3

Power is voltage times current, P = E * I. When current flows through a resistor, a 'voltage drop' ensues. Volts times amperes become watts. Power is dissipated as heat.

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B-5-2-4

What is the best conductor among the following materials?

A.
silicon
B.
aluminium
Correct Answer
C.
copper
D.
carbon

B-5-2-4

The best conductors, in descending order, are: Silver, Copper, Gold and Aluminum. Carbon is a poor conductor, it is used to fabricate resistors. Silicon is used to make 'semiconductors'.

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B-5-2-5

Which type of material listed will most readily allow an electric current to flow?

A.
a dielectric
Correct Answer
B.
a conductor
C.
an insulator
D.
a semiconductor

B-5-2-5

As the name implies, a 'conductor' readily passes electrical current. An Insulator ( synonym = dielectric ) does not let current flow. A resistor conducts but badly.

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B-5-2-6

A length of metal is connected in a circuit and is found to conduct electricity very well. It would be best described as having a:

A.
high wattage
B.
low wattage
Correct Answer
C.
low resistance
D.
high resistance

B-5-2-6

Conductors have LOW resistance. They do not oppose current flow.

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B-5-2-7

The letter "R" is the symbol for:

A.
reactance
Correct Answer
B.
resistance
C.
impedance
D.
reluctance

B-5-2-7

R = Resistance, Z = Impedance, X = Reactance.

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B-5-2-8

The reciprocal of resistance is:

Correct Answer
A.
conductance
B.
reactance
C.
reluctance
D.
permeability

B-5-2-8

Reciprocal = 'the inverse of something'. 1 over resistance yields CONDUCTANCE. Low resistance implies high conductance. High resistance implies little conductance.

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B-5-2-9

Voltage drop means:

Correct Answer
A.
the voltage developed across the terminals of a component
B.
any point in a radio circuit which has zero voltage
C.
the difference in voltage at output terminals of a transformer
D.
the voltage which is dissipated before useful work is accomplished

B-5-2-9

As current flows through electronic components, some voltage is 'lost'. Remember voltage as 'pressure', there is more 'pressure' before a resistor than after it: this represents a 'voltage drop'.

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B-5-2-10

The resistance of a conductor changes with:

A.
current
B.
humidity
Correct Answer
C.
temperature
D.
voltage

B-5-2-10

Temperature affects components and conductors.

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B-5-2-11

The most common material used to make a resistor is:

A.
gold
B.
mica
C.
lead
Correct Answer
D.
carbon

B-5-2-11

Carbon is a poor conductor. Gold and Lead are conductors. Mica is an insulator.

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B-5-3-4

Which electrical circuit will have no current?

A.
A complete circuit
B.
A closed circuit
Correct Answer
C.
An open circuit
D.
A short circuit

B-5-3-4

'Open' circuit = no current ( a loop from one side of the voltage source to the other side does NOT exist, the loop is open ). 'Closed' circuit = current ( a path exists from one side of the voltage source to the other side, current flows, the loop is closed ). 'Short circuit' = heavy current ( a very low resistance path exists between from one side of the voltage source to the other side, large current ensues ).

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B-5-3-5

Which electrical circuit draws too much current?

A.
A closed circuit
B.
An open circuit
Correct Answer
C.
A short circuit
D.
A dead circuit

B-5-3-5

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B-5-7-1

What term means the number of times per second that an alternating current flows back and forth?

A.
Pulse rate
B.
Inductance
Correct Answer
C.
Frequency
D.
Speed

B-5-7-1

Frequency is the number of cycles per second of an Alternating Current (AC). Frequency is expressed in hertz (Hz). One hertz is one cycle per second.

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B-5-7-2

Approximately what frequency range can most humans hear?

A.
0 - 20 Hz
Correct Answer
B.
20 - 20 000 Hz
C.
20 000 - 30 000 Hz
D.
200 - 200 000 Hz

B-5-7-2

Hz = hertz = cycles per second. Frequencies audible to humans range from 20 Hz to 20 000 Hz. Speech frequencies important for intelligibility in communications range from 300 Hz to 3000 Hz.

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B-5-7-3

Why do we call signals in the range 20 Hz to 20 000 Hz audio frequencies?

A.
Because the human ear cannot sense anything in this range
B.
Because this range is too low for radio energy
C.
Because the human ear can sense radio waves in this range
Correct Answer
D.
Because the human ear can sense sounds in this range

B-5-7-3

Hz = hertz = cycles per second. Frequencies audible to humans range from 20 Hz to 20 000 Hz. Speech frequencies important for intelligibility in communications range from 300 Hz to 3000 Hz.

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B-5-7-8

What does 60 hertz (Hz) mean?

Correct Answer
A.
60 cycles per second
B.
6000 metres per second
C.
60 metres per second
D.
6000 cycles per second

B-5-7-8

Hz = hertz = cycles per second. Frequency is the number of cycles per second of an Alternating Current (AC). Frequency is expressed in hertz (Hz). One hertz is one cycle per second.

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B-5-7-9

If the frequency of the waveform is 100 Hz, the time for one cycle is:

Correct Answer
A.
0.01 second
B.
10 seconds
C.
0.0001 second
D.
1 second

B-5-7-9

100 Hz = 100 hertz = 100 cycles per second. The duration of ONE cycle, the "period", is 1 / frequency. In this example, 1 / 100 Hz yields 0.01 second.

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B-5-7-10

Current in an AC circuit goes through a complete cycle in 0.1 second. This means the AC has a frequency of:

A.
1 Hz
B.
100 Hz
C.
1000 Hz
Correct Answer
D.
10 Hz

B-5-7-10

One cycle in 0.1 second, how many cycles in a second ? The duration of ONE cycle, the "period", and frequency have an inverse relation: Frequency is 1 / period. In this example, 1 / 0.1 second yields 10 hertz.

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B-5-7-11

A signal is composed of a fundamental frequency of 2 kHz and another of 4 kHz. This 4 kHz signal is referred to as:

A.
a fundamental of the 2 kHz signal
B.
the DC component of the main signal
C.
a dielectric signal of the main signal
Correct Answer
D.
a harmonic of the 2 kHz signal

B-5-7-11

'Harmonics' are integer MULTIPLES (e.g., 2x, 3x, 4x, 5x,...) of a given frequency. The base frequency is referred to as the 'fundamental'.

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B-5-11-9

A force of repulsion exists between two _________ magnetic poles.

A.
unlike
B.
positive
C.
negative
Correct Answer
D.
like

B-5-11-9

key word: REPULSION. 'Like' magnetic poles repulse each other. 'Unlike' magnetic poles attract one another.

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B-5-11-10

A permanent magnet would most likely be made from:

Correct Answer
A.
steel
B.
copper
C.
aluminum
D.
brass

B-5-11-10

Copper, aluminum and brass are impervious to magnetic fields.

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B-5-13-1

How is a voltmeter usually connected to a circuit under test?

A.
In quadrature with the circuit
B.
In phase with the circuit
Correct Answer
C.
In parallel with the circuit
D.
In series with the circuit

B-5-13-1

key word: VOLTMETER. An instrument to measure voltage. The voltmeter is always connected in parallel to measure a difference of potential between two points, across a component, etc.

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B-5-13-2

How is an ammeter usually connected to a circuit under test?

A.
In quadrature with the circuit
B.
In phase with the circuit
C.
In parallel with the circuit
Correct Answer
D.
In series with the circuit

B-5-13-2

key word: AMMETER. Ammeter comes from the words ampere + meter, it is used to measure current. Current flows THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-3

What does a multimeter measure?

Correct Answer
A.
Voltage, current and resistance
B.
Resistance, capacitance and inductance
C.
Resistance and reactance
D.
SWR and power

B-5-13-3

Common multimeters can measure the three basic electrical units: voltage (E), current (I) and resistance (R).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-4

The correct instrument to measure plate current or collector current of a transmitter is:

A.
a voltmeter
Correct Answer
B.
an ammeter
C.
an ohmmeter
D.
a wattmeter

B-5-13-4

key word: CURRENT. Ammeter comes from the words ampere + meter, it is used to measure current.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-5

Which of the following meters would you use to measure the power supply current drawn by a small hand-held transistorized receiver?

A.
An electrostatic voltmeter
Correct Answer
B.
A DC ammeter
C.
An RF ammeter
D.
An RF power meter

B-5-13-5

key word: CURRENT. Ammeter comes from the words ampere + meter, it is used to measure current.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-6

When measuring current drawn from a DC power supply, it is true to say that the meter will act in circuit as:

A.
an extra current drain
B.
an insulator
Correct Answer
C.
a low value resistance
D.
a perfect conductor

B-5-13-6

This is a bit of a catch. A PERFECT conductor would exhibit ZERO resistance. An ammeter actually has a very low resistance. [ For example, a 10 A ammeter can have a resistance of 0.005 ohms, a 1 A ammeter can have 0.05 ohms and a 500 mA ammeter can introduce 0.2 ohms of resistance in the circuit. ]

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-7

When measuring the current drawn by a receiver from a power supply, the current meter should be placed:

A.
in parallel with one of the receiver power leads
Correct Answer
B.
in series with one of the receiver power leads
C.
in series with both receiver power leads
D.
in parallel with both receiver power supply leads

B-5-13-7

Ammeter comes from the words ampere + meter, it is used to measure current. Current flows THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-8

Potential difference is measured by means of:

Correct Answer
A.
a voltmeter
B.
a wattmeter
C.
an ohmmeter
D.
an ammeter

B-5-13-8

The voltmeter is always connected in parallel to measure a difference of potential between two points, across a component, etc.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-9

The instrument used for measuring the flow of electrical current is the:

A.
wattmeter
B.
voltmeter
Correct Answer
C.
ammeter
D.
faradmeter

B-5-13-9

Ammeter comes from the words ampere + meter, it is used to measure current. Current flow THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-5-13-10

In measuring volts and amperes, the connections should be made with:

Correct Answer
A.
the voltmeter in parallel and ammeter in series
B.
the voltmeter in series and ammeter in parallel
C.
both voltmeter and ammeter in series
D.
both voltmeter and ammeter in parallel

B-5-13-10

The voltmeter is always connected in parallel to measure a difference of potential between two points, across a component, etc. Ammeter comes from the words Ampere + meter, it is used to measure current. Current flow THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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