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Subelement T6
Electrical components; circuit diagrams; component functions
Section T6A
Electrical components: fixed and variable resistors; capacitors and inductors; fuses; switches; batteries
What electrical component opposes the flow of current in a DC circuit?
  • Inductor
  • Resistor
  • Voltmeter
  • Transformer

It may help to remember RESISTor as a synonym for oppose, as in oppose the flow of current

Resistor symbol Resistor Symbol

https://en.wikipedia.org/wiki/Resistor

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Tags: resistance electronics electrical components arrl chapter 3 arrl module 6

What type of component is often used as an adjustable volume control?
  • Fixed resistor
  • Power resistor
  • Potentiometer
  • Transformer

A potentiometer (pot) can be configured as a user controlled variable resistor. This change in resistance in turn controls the volume.

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Tags: resistance electronics electrical components arrl chapter 3 arrl module 6

What electrical parameter is controlled by a potentiometer?
  • Inductance
  • Resistance
  • Capacitance
  • Field strength

A Potentiometer is sometimes called a variable resistor; the schematic symbol looks just like a resistor (a line with a section in the middle that is jagged up and down before continuing straight), but has an arrow pointing perpendicular at the center of the symbol (at the zig-zag section). Potentiometer symbol Potentiometer Symbol

Potentiometers usually have three poles, one on each side (with the total resistance of the potentiometer between them) and one in the middle which moves back and forth. The total resistance from the middle terminal to an edge is the inverse of the resistance from the middle to the other edge, meaning that as you slide, turn, or otherwise adjust the potentiometer the resistance on one side grows while the other shrinks.

Take a look at the wikipedia article for more information.

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Tags: resistance electronics electrical components arrl chapter 3 arrl module 6

What electrical component stores energy in an electric field?
  • Resistor
  • Capacitor
  • Inductor
  • Diode

There are two questions in the pool that are very similar; one asks about a component storing energy in an electric field, the other in a magnetic field. The electric field is a capacitor; it consists of at least two conductors seperated by an insulator (or dielectric). When voltage is applied to the capacitor it will initially pull a lot of current, dropping the voltage and slowly charging up an electric field (due to the difference in potential between the positive and negative charges on the capacitor). Capacitors thus store energy in the electric field, and once they have charged up they no longer allow current to pass through.

If the power source (such as a battery) is removed, the capacitor will begin to discharge, initially keeping the circuit at exactly the same voltage as before with the current dying down until the voltage can no longer be maintained with the energy remaining in the electric field. For this reason, we say that a capacitor resists change in voltage.

Think "MICE:" "(M)agnetic field, (I)nductor. (C)apacitor, (E)lectric field.

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Tags: capacitance electronics electrical components arrl chapter 3 arrl module 6

What type of electrical component consists of two or more conductive surfaces separated by an insulator?
  • Resistor
  • Potentiometer
  • Oscillator
  • Capacitor

A Capacitor is an electrical component that stores energy in an electric field. It consists of at least two conductors seperated by an insulator (or dielectric).

Capacitor symbol The schematic symbol looks just like its construction.

When voltage is applied to the capacitor it will initially pull a lot of current, dropping the voltage and slowly charging up an electric field (due to the difference in potential between the positive and negative charges on the capacitor). Capacitors thus store energy in the electric field, and once they have charged up they no longer allow current to pass through.

If the power source (such as a battery) is removed, the capacitor will begin to discharge, initially keeping the circuit at exactly the same voltage as before with the current dying down until the voltage can no longer be maintained with the energy remaining in the electric field. For this reason, we say that a capacitor resists change in voltage.

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Tags: capacitance electronics electrical components arrl chapter 3 arrl module 6

What type of electrical component stores energy in a magnetic field?
  • Resistor
  • Capacitor
  • Inductor
  • Diode

There are two questions in the pool that are very similar; one asks about a component storing energy in an electric field, the other in a magnetic field. The magnetic field is an inductor; it generally consists of a coil of wire.

Inductor symbol The inductor symbol looks very much like its construction.

The characteristics of the inductor vary drastically depending on whether or not the wire has a ferrite (susceptible to magnetism) core inside; if it does, the ferrite core becomes itself a magnet. This is how electromagnets are made, such as in the classic electronics experiment of wrapping insulated wire around a nail and turning it into an electromagnet.

When current is applied to an inductor, it initially resists the current's flow because of the magnetic field that is generated as the current begins to move through the coil; as the magnetic field charges up, the resistance to the current weakens until the current flows as though through a straight wire. However, when the current source is removed the magnetic field will begin to discharge, keeping the current constant for as long as it can, increasing the voltage until the energy runs out. This is why inductors (including transformers) can be used to build "shockers", or small electronic devices that can produce enough voltage to shock someone, but without enough current to injure them (but hurt them in the case of tazers). The inductor as it discharges pushes the voltage up until it can jump the gap and "spark".

If you can remember that an inductor is a coil of wire and that a coil around a nail creates an electromagnet, then you should be able to remember that an inductor stores energy in a magnetic field.

Mnemonic (memory) hint: Think of "MICE." (M)agnetic field, (I)nductor. (C)apacitor, (E)lectric field.

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Tags: inductance electronics electrical components arrl chapter 3 arrl module 6

What electrical component usually is constructed as a coil of wire?
  • Switch
  • Capacitor
  • Diode
  • Inductor

An inductor generally consists of a coil of wire.

Inductor Symbol The schematic symbol looks very much like its construction.

The characteristics of the inductor vary drastically depending on whether or not the wire has a ferrite (susceptible to magnetism) core inside; if it does, the ferrite core becomes itself a magnet. This is how electromagnets are made, such as in the classic electronics experiment of wrapping insulated wire around a nail and turning it into an electromagnet.

When current is applied to an inductor, it initially resists the current's flow because of the magnetic field that is generated as the current begins to move through the coil; as the magnetic field charges up, the resistance to the current weakens until the current flows as though through a straight wire. However, when the current source is removed the magnetic field will begin to discharge, keeping the current constant for as long as it can, increasing the voltage until the energy runs out. This is why inductors (including transformers) can be used to build "shockers", or small electronic devices that can produce enough voltage to shock someone, but without enough current to really hurt them. The inductor as it discharges pushes the voltage up until it can jump the gap and "spark".

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Tags: inductance electronics electrical components arrl chapter 3 arrl module 6

What electrical component is used to connect or disconnect electrical circuits?
  • Magnetron
  • Switch
  • Thermistor
  • All of these choices are correct

Possibly the most common example of this is a lightswitch in your house; when it is on, it connects the electrical circuit that the light in your room is on. When you turn it off, it disconnects the circuit.

There are many different kinds of switches, but they still all just connect (turn on) or disconnect (turn off) a circuit.

These are not capable of connecting or disconnecting a circuit:

A Magnetron is usually a high powered vacuum tube that generate microwaves.

A Thermistor is a type of resistor whose resistance varies significantly with temperature.

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Tags: electronics electrical components arrl chapter 3 arrl module 6

What electrical component is used to protect other circuit components from current overloads?
  • Fuse
  • Capacitor
  • Inductor
  • All of these choices are correct

A fuse acts like a wire until excessive current flows through it. Fuses are rated in amps. It is very important to replace blown fuses with the same rating and same type (such as fast blow vs slow blow). Otherwise the protected circuit may fail catastrophically including igniting a fire.

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Tags: electronics electrical components arrl chapter 3 arrl module 6

Which of the following battery types is rechargeable?
  • Nickel-metal hydride
  • Lithium-ion
  • Lead-acid gel-cell
  • All of these choices are correct

Yes, all of these are rechargeable. A zinc-carbon battery is not. You just have to remember this.

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Tags: arrl chapter 5 arrl module 12

Which of the following battery types is not rechargeable?
  • Nickel-cadmium
  • Carbon-zinc
  • Lead-acid
  • Lithium-ion

The chemical reactions of Carbon-zinc type batteries are not reversable, unlike Nickel-cadmium, lead-acid, and Lithium-ion type batteries.

A way to remember this if you have trouble is that you Can't Zap a Carbon-Zinc battery with an electric charge to recharge it!

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Tags: dc power batteries electrical components arrl chapter 5 arrl module 12

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