Chap. 4 Summary Flashcards by Jessica Millstead

The smallest part of an element that can exist:

An atom

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An atom consists of :

Electrons, Protons, & Neutrons

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[———] travel in orbits around the center, or nucleus, of the atom.

Electrons

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Electrons have what type of electrical charges?

Negative

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A nucleus is made up of [—–] and [——-] that are bound tightly together.

Protons and neutrons

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Protons have [——] charge

positive

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Neutrons carry what kind of charges

neutral

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The number of protons and electrons is [———] in any atom.

equal

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When bound electrons are in the majority of an element or compounded material, the material is an [———-]

insulator

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Conductors are :

Materials that contain atoms with free electrons.

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When will the flow of free electrons take place?

Only when there is a complete circuit and the source produces a difference in electrical potential in the circuit.

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There are two types of ejectrical current found in small engine applications:

Direct current (DC) & alternating current (AC)

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Direct current flows:

in one direction only.

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How does alternating current flow?

In one direction, stops, and then flows in the opposite direction.

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What is an Ampere (A)?

A measurement of the number of electrons flowing past any given point in a specific period of time.

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The difference in electrical potential between two points in a circuit is measured in what?

(v) Volts

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Resistance to electron flow is measured in:

Ohms

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What is Ohms law used for?

To calculate an unknown circuit value when two other values are known.

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What things do all circuits consist of?

A source of electricity, a load, and electrical conductors that connect the source to the load.

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There are [—-] basic types of electrical circuits.

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What are the 3 basic types of electrical circuits:

Series circuits
Parallel circuits
series -parallel circuits

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What happens in a series circuit?

Current flows from the power source to each device in turn and then flows back to the source.

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What kind of circuits have more than one path for the current to flow in the circuit?

Parallel

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What kind of circuits have some electrical devices connected in series and others in parallel?

Series Parallel circuits

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All magnets produce:

A magnetic field.

What happens when a wire is moved past a magnet?

The magnetic field is cut by the wire and current flows in the wire.

What is developed around a conductor when electrons flow through the conductor?

A magnetic field

The electrical wire used in small engine applications generally consists of:

A metal conductor that is encased in plastic insulation.

Wire and cable sizes are expressed how:

By a gauge number.

What is indicated by the gauge number of wires and cables:

The cross- sectional area of the conductor.

What is used to control the flow of current in an electric circuit?

A switch

There are many types of [-------] used in small engines and related implements.

Switches

What is a device that converts electrical energy into mechanical energy?

A solenoid

Another name for mechanical energy:

Motion

What consists of a coil of wire that surrounds a metal rod or plunger?

A Solenoid

Relays are used as what

electrical switches.

What do relays that are used as electrical switches, do?

Allow a relatively low current to be used to control a high current

An electrical device designed to increase or decrease voltage or current levels is a:

Transformer

What devices are used to protect a circuit from excessive current flow.

Circuit protection devices

What do common circuit protection devices include?

Fuses. Fusable links. circuit breakers.

What term is used to refer to any electrical component, assembly, circuit, or system that uses semi conductor devices?

Electronics

A two-element solid-state electronic device that acts as a one-way valve:

A semiconductor diode

What does a semiconductor diode do?

Conduct current in one direction and remain nonconductive in the reverse direction.

A solid-state device that can be used as a switch:

A transistor

A length of wire with alligator clips attached to each end:

A jumper wire

A jumper wire can be used for what purposes?

To bypass components or to apply source voltage directly to a component.

A test light is used for what?

To check for continuity or the presence of voltage in an electrical circuit.

Voltmeters measure:

voltage

Ammeter measure:

Current

Ohmmeters measure:

resistance

Voltmeters, ammeters and ohmmeters are generally combined in a single piece of test equipment called a :

Multimeter

Continuity

The presence of a complete path for current flow

An atom contains:

Electrons, Neutrons, and Protons

Electrons have what kind of electrical charge?

Negative

[T - or- F] Bound electrons are closely held electrons that never leave the atom.

True

Electricity can be produced how?

chemically, mechanically and statically

[T-or-F] Alernating current is produced by a battery

False

Volts are:

units of measurement used to find the difference in electrical potential between two points in a circuit.

ohms law

I = E/R

In a series circuit, [-------] is the same in all parts of the curcuit.

Current

In a parallel curcuit,[------------] is the same in all parts of the circuit

Voltage

[True - or- False] Voltage drop is the decrease in voltage as current passes through a resistance.

True

[True-or-False] The magnetic field that surrounds a magnet leaves the south pole of the magnet and re-enters through the north pole.

True

When electrons flow through a conductor, a [---------------] is developed around the conductor

magnetic field

[True-or-False] The larger the diameter of a wire or cable, the larger the gauge number size.

False

[True-or-False] A switch is used to control the flow of current in an electric circuit

True

A solenoid converts electrical energy into [-------] energy.

Mechanical [Motion]

Solid-state devices are made from [-------------] materials.

semiconductor

[True-or-False] A diode acts as a one-way valve.

True

Powered test lights are used to check for [------------] in a circuit.

Continuity

[True-or-False] When measuring current, the ammeter should be connected in series with the circuit

True

When using an [--------------] the power must be off in the circuit being tested.

Ohmmeter

Explain why current is created in a conductor that is moved past a magnet.

****? Because the magnetic field increases?****

What is the benefit of using a stranded conductor?

They are more flexible than solid conductors. They are ideal for use in high-vibration applications, which might weaken or break a solid conductor.

In what applications would stranded wire be used in a small engine powered implement?

High vibration applications.

@@@? Why does the number of turns in each coil of a transformer affect the voltage produced at the output?

When replacing a fuse, why is it important to use a replacement with the same current rating as the blown fuse?

Because if you use one eith a higher current rating, it can allow too much current to flow in a curcuit, potentially damaging the circuit and causing an electrical fire.

What advantages do transistors have over relays?

The transistor is much smaller than a relay and has no moving parts to wear out.

What types of problems could cause excessive resistance in an electric circuit?

Electronic switching devices have replaced mechanical switches in small engine ignition systems. What advantages do you think these electronic devices offer over their mechanical predecessors?

Is it acceptable to use jumper wires to bypass a blown fuse? Explain why or why not.

Electric motors have replaced small engines on a number of handheld yard implements, such as string trimmers and leaf blowers. What are the advantages and disadvantages of these electric motor-driven implements?