AS112 Electrical Review Flashcards

Flashcards based on the AS112 review quiz covering electrical fundamentals, Ohm's law, component color codes, meter operations, and aircraft battery care.

What are valence electrons?

Valence electrons are the electrons located in the outermost shell of an atom.

What are materials that have $5$ or more valence electrons known as?

Insulators.

What are materials that have less than $4$ valence electrons known as?

Conductors.

From where does electron actual current flow?

From negative to positive.

According to conventional theory, from where to where does electricity flow?

From positive to negative.

What does the acronym E.M.F. stand for?

Electromotive Force.

What unit is E.M.F. measured in?

Volts ($V$).

What letter is used to represent voltage (E.M.F.)?

The letter $E$.

How is current defined?

Current is defined as the flow of electrons through a conductor.

In what unit is current measured?

Amperes or Amps ($A$).

What letter is used to designate current?

The letter $I$.

How is electrical resistance defined?

Resistance is defined as the opposition to the flow of electric current.

In what unit is resistance measured?

Ohms ($\Omega$).

What letter is used to designate resistance?

The letter $R$.

How is electrical power defined?

Power is defined as the rate at which electrical energy is expanded or work is done.

In what unit is power measured?

Watts ($W$).

What letter is used to designate power?

The letter $P$.

What is $0.0056$ volts converted to milli-volts?

$$5.6\,mV$$

What is $24,500$ ohms converted to kilo-ohms?

$$24.5\,k\Omega$$

What is $31.7$ Mega-ohms converted to ohms?

$$31,700,000\,\Omega$$

What is $5.3$ micro-amps converted to amps?

$$0.0000053\,A$$

What are the two basic formulas used to represent Ohm's Law and electrical power?

$E = I \times R$ and $P = I \times E$

What is the voltage required to push $3\,A$ through $800\,\Omega$ of resistance?

$$2400\,V$$

How much resistance is present in a $24\,V$ circuit with $4.8\,A$ of current?

$$5\,\Omega$$

How much current flows through a circuit having $50\,k\Omega$ of resistance and $100\,V$?

$0.002\,A$ (or $2\,mA$)

What is the power used by a circuit having $1.2\,A$ through $150\,\Omega$ of resistance?

$$216\,W$$

What is the total power of a $24\,V$ circuit having four $1200\,\Omega$ resistors connected in series?

$$0.12\,W$$

What electrical parameter remains constant throughout a series circuit?

Current ($I$).

What electrical parameter remains constant across all branches in a parallel circuit?

Voltage ($E$).

What does the first band on a resistor designate?

The first digit of the resistance value.

What does the second band on a resistor designate?

The second digit of the resistance value.

What does the third band on a resistor designate?

The multiplier (number of zeros to add).

What does the fourth band on a resistor designate?

The resistance tolerance percentage.

If there is no fourth band on a resistor, what is its tolerance?

$$\pm 20\%$$

What is the resistance value and tolerance of a resistor color-coded Green, Yellow, Red, Silver?

$5400\,\Omega \pm 10\%$ (or $5.4\,k\Omega \pm 10\%$).

What is the resistance value and tolerance of a resistor color-coded Blue, Brown, Orange, Gold?

$61,000\,\Omega \pm 5\%$ (or $61\,k\Omega \pm 5\%$).

Do magnetic lines of flux go through or go around soft iron?

Magnetic lines of flux go through soft iron.

Externally, magnetic field lines flow from which pole to which pole?

From North to South.

How does static electricity distribute on different shaped surfaces?

Static electricity distributes evenly on smooth, rounded surfaces, but collects on sharp, pointed surfaces.

What is the left-hand rule for conductors?

Grasp the conductor with your left hand pointing your thumb in the direction of electron flow, and your fingers will wrap in the direction of the magnetic lines of flux.

What is the left-hand rule for coils?

Wrap the fingers of your left hand around the coil in the direction of electron flow, and your thumb will point toward the north pole of the electromagnet.

How does a rheostat control power in a circuit?

By varying the current through the circuit.

How does a potentiometer control power in a circuit?

By varying the voltage across the circuit.

How does increasing the length of a wire affect its resistance?

The resistance will increase.

How does increasing the diameter of a wire affect its resistance?

The resistance will decrease.

What type of circuit breakers must aircraft use?

Trip-free circuit breakers.

How can excessive static charges be eliminated on an aircraft in flight?

By the use of static discharge wicks.

What is electromagnetic induction?

Electromagnetic induction occurs when electricity is produced by moving a conductor through a magnetic field.

What is used to statically balance aircraft structures to the same electrical potential?

Bonding straps.

According to Kirchhoff's voltage law, if a circuit contains a $12\,V$ battery, what total voltage will the circuit loads use?

$$12\,V$$

How is a voltmeter connected into a circuit?

In parallel with the load or circuit.

How is an ammeter connected into a circuit?

In series with the circuit.

What are the proper steps for connecting an ohmmeter into a circuit?

Ensure the circuit power is isolated/OFF, zero/calibrate the meter, and connect the meter leads in parallel across the de-energized component.

What type of meter supplies its own internal power source?

An ohmmeter.

What meter is used to test electrical insulation resistance?

A megohmmeter (or Megger).

What meter is used to test bonding straps?

A micro-ohmmeter (or low-resistance bonding meter).

What does a measured discharge test indicate to an aircraft mechanic?

The capacity and overall state of health of a battery in ampere-hours.

What is deep cycling a battery?

Deep cycling involves completely discharging a battery down to zero volts and then fully recharging it to equalize cells and remove memory effects.

How many series-connected cells are in a $12\,V$ lead-acid battery?

$6$ cells.

During battery installation into an aircraft, when should the negative terminal be connected?

The negative terminal should be connected last.

What is the specific gravity of the electrolyte in a fully charged lead-acid battery?

Between $1.275$ and $1.300$.

What substance is used to neutralize the electrolyte of a lead-acid battery?

Baking soda (sodium bicarbonate) mixed with water.

What substance is used to neutralize the electrolyte of a Ni-Cad battery?

Boric acid solution or diluted vinegar.

How are aircraft batteries rated?

In Ampere-hours ($Ah$) and terminal voltage.

What is a battery?

A battery is a device consisting of two or more cells that converts chemical energy into electrical energy.

What happens to the electrolyte in a lead-acid battery during discharge?

The electrolyte's specific gravity decreases because sulfuric acid leaves the liquid to form lead sulfate on the plates, leaving mostly water.