Basic Electrical Concepts Alıştırma Soruları — Armed Services Vocational Aptitude Battery (ASVAB) — Sayfa 6

Soru 101Soru →

An electronics technician tests a DC audio indicator module connected to a $24\text{ V}$ power supply. An in-line meter measures a steady current flow of $80\text{ mA}$ through the component. According to Ohm's law, what is the electrical resistance of the module in ohms ( $\Omega$ )?

Cevabı ve açıklamayı göster

Cevap: 300

Cevap

The total resistance of the module is

300\text{ }\Omega

.

According to Ohm's law (

V = I \times R

), resistance equals voltage divided by current (

R = \frac{V}{I}

). Converting

80\text{ mA}

to standard amperes gives

0.08\text{ A}

. Dividing the

24\text{ V}

source by

0.08\text{ A}

yields a resistance of

300\text{ }\Omega

.

Adım Adım Çözüm

1

Convert current from milliamperes (mA) to base amperes (A)

80\text{ mA} = 80 \times 10^{-3}\text{ A} = 0.08\text{ A}

Ohm's law requires current to be expressed in standard SI units (amperes) when working with volts and ohms.

2

Rearrange Ohm's law (

V = I \times R

) to isolate resistance (

R

)

R = \frac{V}{I}

Dividing both sides of the standard Ohm's law equation by current isolates the unknown resistance.

3

Substitute the known voltage (

24\text{ V}

) and current (

0.08\text{ A}

) into the formula

R = \frac{24\text{ V}}{0.08\text{ A}} = 300\text{ }\Omega

Performing the division calculates the exact resistance value in ohms.

Anahtar Kavram

Ohm's law resistance calculation with metric prefix conversion (

R = \frac{V}{I}

)

Tahmini Süre:1m 0s

Soru 102Soru →

When an auxiliary lighting circuit in an electrical system is active, a meter records a current of $1.5\text{ A}$ . What does this electrical current measurement physically represent?

The electromotive force or electrical pressure driving charges through the conductor

The rate at which electric charge flows past a given point in the circuit

The physical opposition that restricts the passage of electrons through the wire

The rapid back-and-forth oscillation of charge carriers between opposite terminals

Cevabı ve açıklamayı göster

Cevap: The rate at which electric charge flows past a given point in the circuit

Cevap

The rate at which electric charge flows past a given point in the circuit

Electric current (

I

) is defined as the rate at which electric charge flows past a cross-sectional point in a conductor. One ampere equals one coulomb of charge passing a point per second (

1\text{ A} = 1\text{ C/s}

).

Adım Adım Çözüm

1

Identify the physical definition of electrical current (

I

)

Current represents the quantity of electrical charge (

Q

) passing through a cross-section of a conductor per unit time (

t

), expressed as

I = \frac{Q}{t}

.

Understanding the base definition of the ampere (

1\text{ A} = 1\text{ Coulomb/second}

) establishes what is being measured.

2

Distinguish current from related electrical properties like voltage and resistance

Voltage is the driving pressure (EMF), resistance is the opposition to flow, while current is the actual movement rate of the charges.

Eliminates common misconceptions regarding electrical circuit parameters.

Anahtar Kavram

Electric current is the rate of flow of electric charge over time, quantified in amperes.

Tahmini Süre:35s

Soru 103Soru →

An automotive spotlight operates on a $12\text{ V}$ direct current (DC) electrical system and draws a steady current of $4\text{ A}$ . How much electrical power is consumed by the spotlight?

3\text{ W}

48\text{ W}

16\text{ W}

192\text{ W}

Cevabı ve açıklamayı göster

Cevap: $48\text{ W}$

Cevap

The power consumed by the spotlight is

48\text{ W}

.

According to Watt's Law, electrical power (

P

) is determined by multiplying voltage (

V

) by current (

I

), using the formula

P = V \times I

. Substituting

12\text{ V}

and

4\text{ A}

gives

P = 12\text{ V} \times 4\text{ A} = 48\text{ W}

.

Adım Adım Çözüm

1

Identify the given electrical values from the problem statement.

Voltage (

V

) =

12\text{ V}

, Current (

I

) =

4\text{ A}

.

Establishing the known quantities determines which form of Watt's Law to apply.

2

Select the appropriate Watt's Law power formula relating power, voltage, and current.

P = V \times I

Electrical power in watts equals the product of potential difference in volts and current in amperes.

3

Substitute the values into the formula and calculate.

P = 12\text{ V} \times 4\text{ A} = 48\text{ W}

Carrying out the multiplication yields the total power dissipated.

Anahtar Kavram

Watt's Law relates electrical power (

P

) to voltage (

V

) and current (

I

) through the formula

P = V \times I

.

Tahmini Süre:45s

Soru 104Soru →

An electrical technician is evaluating four substances for an electronics assembly based on how easily charge carriers move through their atomic lattices. What is the correct order of these materials when arranged from highest electrical conductivity (greatest electron flow) to lowest electrical conductivity (highest resistance to current flow) at room temperature ( $25^\circ\text{C}$ )?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

Silver, followed by Intrinsic Germanium, Intrinsic Silicon, and finally Mica.

Electrical conductivity is determined by the density of free charge carriers available in a material's conduction band. Silver is an excellent metallic conductor with free electrons that readily drift under an applied electric field. Germanium and silicon are Group IV semiconductors; because germanium has a narrower forbidden bandgap (

0.67\text{ eV}

) than silicon (

1.12\text{ eV}

), more electron-hole pairs are thermally excited across the gap at room temperature, making germanium more conductive than silicon. Mica is an inorganic insulator with tightly held valence electrons and a very wide forbidden energy gap, giving it the lowest electrical conductivity in the sequence.

Adım Adım Çözüm

1

Identify the metallic conductor

Silver is identified as the conductor with the highest concentration of free valence electrons.

Metals have overlapping valence and conduction bands, providing high electrical conductivity.

2

Compare the semiconductor bandgaps

Intrinsic Germanium (

E_g \approx 0.67\text{ eV}

) has higher conductivity than Intrinsic Silicon (

E_g \approx 1.12\text{ eV}

).

A smaller bandgap allows more valence electrons to bridge into the conduction band at room temperature.

3

Identify the electrical insulator

Mica is placed last with the lowest electrical conductivity.

Insulators have full valence bands separated from conduction bands by large forbidden energy gaps.

Anahtar Kavram

Ranking material electrical conductivity based on atomic structure, valence electron availability, and energy bandgap size across conductors, semiconductors, and insulators.

Tahmini Süre:1m 30s

Soru 105Soru →

An industrial controller module requires a total electromotive force (EMF) of $0.12\text{ kV}$ for its backup power rail. If standard $1.5\text{ V}$ alkaline cells are connected in series-aiding to supply the rail, how many cells are required?

Cevabı ve açıklamayı göster

Cevap: 80

Cevap

80 cells

The total requirement is

0.12\text{ kV}

, which equals

120\text{ V}

. Since series-aiding cells add their electromotive forces directly, dividing the total required voltage of

120\text{ V}

by

1.5\text{ V}

per cell gives exactly

80

cells.

Adım Adım Çözüm

1

Convert the required electromotive force from kilovolts (kV) to standard volts (V)

0.12\text{ kV} \times 1000 = 120\text{ V}

The prefix kilo- denotes a multiplier of

1000

, so the potential difference must be converted to base units to match individual cell ratings.

2

Calculate the number of series cells needed by dividing total EMF by the EMF of a single cell

n = \frac{120\text{ V}}{1.5\text{ V/cell}} = 80\text{ cells}

When electrical cells are connected in series-aiding configuration, their individual voltages add directly (

V_{\text{total}} = n \times V_{\text{cell}}

).

Anahtar Kavram

Series electromotive force summation and metric prefix voltage conversion

Tahmini Süre:1m 0s

Soru 106Soru →

An electronics technician is analyzing the atomic structure and thermal-electrical properties of three unknown solid materials for a specialized circuit application. Material X possesses exactly four valence electrons and its electrical conductivity increases when heated. Material Y possesses a single, loosely bound valence electron and its electrical conductivity decreases when heated. Material Z has a completely filled outermost shell with tightly bound valence electrons. Based on these fundamental characteristics, which of the following correctly classifies these three materials?

Material X is a semiconductor, Material Y is a conductor, and Material Z is an insulator.

Material X is a conductor, Material Y is a semiconductor, and Material Z is an insulator.

Material X is an insulator, Material Y is a conductor, and Material Z is a semiconductor.

Material X is a semiconductor, Material Y is an insulator, and Material Z is a conductor.

Cevabı ve açıklamayı göster

Cevap: Material X is a semiconductor, Material Y is a conductor, and Material Z is an insulator.

Cevap

Material X is a semiconductor, Material Y is a conductor, and Material Z is an insulator.

The correct answer accurately synthesizes the relationship between atomic structure and electrical behavior. Semiconductors (Material X) are defined by having exactly 4 valence electrons; as they are heated, thermal energy frees more electrons, increasing conductivity. Conductors (Material Y) typically have 1 to 3 loosely bound valence electrons; as they are heated, increased atomic vibrations impede electron flow, decreasing conductivity. Insulators (Material Z) are characterized by full, tightly bound valence shells, preventing electron flow entirely.

Adım Adım Çözüm

1

Analyze the properties of Material X.

Material X is identified as a semiconductor.

It has exactly four valence electrons (Group IV elements like Silicon and Germanium) and its conductivity increases with heat (negative temperature coefficient of resistance) as thermal energy pushes electrons across the narrow band gap.

2

Analyze the properties of Material Y.

Material Y is identified as a conductor.

It has a single loosely bound valence electron (like Copper, Silver, or Gold), which makes it highly conductive. Its conductivity decreases with heat (positive temperature coefficient) due to increased atomic lattice vibrations scattering the free electrons.

3

Analyze the properties of Material Z.

Material Z is identified as an insulator.

It has a completely filled outermost shell with tightly bound electrons (like Mica or Glass), meaning there are no free electrons available for electrical conduction under normal conditions.

4

Combine the evaluations to select the correct classification.

The correct classification is: X = semiconductor, Y = conductor, Z = insulator.

This is the only combination that accurately aligns with the fundamental atomic and thermal theories of electrical materials.

Anahtar Kavram

Atomic structure (valence electrons) and thermal-electrical properties of basic electronic materials.

Tahmini Süre:1m 30s

Soru 107Soru →

In electrical circuits, the physical characteristics of a conductor govern its opposition to current flow. Match each conductor modification on the left with its resulting effect on electrical resistance on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

Extending length matches with increasing resistance due to a longer path; increasing diameter matches with decreasing resistance due to a wider cross-section; elevating temperature matches with increasing resistance due to increased atomic vibrations; replacing copper with nichrome matches with increasing resistance due to higher intrinsic resistivity.

Each modification is correctly paired according to the fundamental resistance formula

R = \rho \frac{L}{A}

and the positive temperature coefficient of metallic conductors: increasing length increases

R

, increasing cross-sectional area decreases

R

, heating the metal increases

R

, and selecting a higher resistivity material increases

R

.

Adım Adım Çözüm

1

Analyze the relationship between wire length and resistance using

R = \rho \frac{L}{A}

Resistance increases linearly as length increases.

Electrons encounter more resistive material over a longer distance.

2

Analyze the relationship between wire cross-sectional area (thickness) and resistance

Resistance decreases as area increases.

A greater cross-sectional area allows more electrons to pass simultaneously with fewer collisions.

3

Determine the effect of thermal energy on metallic conductors

Resistance increases as temperature rises.

Thermal energy causes metal lattice ions to vibrate more vigorously, impeding the drift of free electrons.

4

Compare material resistivity (

\rho

) between copper and nichrome

Nichrome creates greater resistance than copper of identical dimensions.

Nichrome is a high-resistivity alloy specifically designed to impede current flow and generate heat.

Anahtar Kavram

The resistance of a conductor is determined by its physical dimensions (length and cross-sectional area), material resistivity, and operating temperature.

Tahmini Süre:45s

Soru 108Soru →

While diagnosing a control circuit in an industrial machine, a technician measures the flow of electric current through a closed direct-current (DC) loop. Which statement accurately describes the relationship between the electrical current and charge carriers in this circuit?

Electric current is the electromotive pressure maintained across terminals that exists even when no physical charge is in motion.

Electric current is the continuous rate of charge transfer through the conductor, produced by free electrons drifting toward the positive potential.

Electric current in this DC circuit continuously reverses direction back and forth through the load at a standard cyclic frequency.

Electric current is the movement of bound atomic charges traveling exclusively along the outer protective insulating sheath.

Cevabı ve açıklamayı göster

Cevap: Electric current is the continuous rate of charge transfer through the conductor, produced by free electrons drifting toward the positive potential.

Cevap

Electric current is the continuous rate of charge transfer through the conductor, produced by free electrons drifting toward the positive potential.

Electric current is defined as the rate at which charge passes through a cross-section of a conductor (

I = Q/t

). In standard solid conductors under direct current (DC), the charge carriers are mobile valence electrons that drift unidirectionally toward the positive terminal of the circuit.

Adım Adım Çözüm

1

Identify the fundamental definition of electric current.

Current (

I

) is defined as the quantity of electrical charge (

Q

) passing a cross-section of a conductor per unit of time (

t

), expressed mathematically as

I = \frac{Q}{t}

.

Establishing the definition of current separates it from static potential or resistance.

2

Determine the physical charge carrier behavior in a direct-current metallic circuit.

In metallic conductors, current is carried by negatively charged free valence electrons that drift away from the negative polarity toward the positive terminal in a unidirectional path.

Direct current maintains a constant single direction of charge carrier drift.

Anahtar Kavram

Electric current is the time rate of charge flow through a conductor, with electrons physically moving toward the positive terminal in a DC circuit.

Tahmini Süre:45s

Soru 109Soru →

Match each Watt's Law power formula or electrical power unit on the left with its corresponding definition or application condition on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

P = V \times I

matches power from voltage and current;

P = I^2 R

matches power from current and resistance;

P = \frac{V^2}{R}

matches power from voltage and resistance;

1\text{ Watt (W)}

matches the unit equivalent to one joule per second.

Each formula represents a direct algebraic variation of Watt's Law derived by combining

P = V \times I

with Ohm's Law (

V = IR

), and the watt is defined as one joule per second.

Adım Adım Çözüm

1

Identify the base relationship of Watt's Law

P = V \times I

Electrical power is defined as the rate at which electrical energy is transferred, calculated by multiplying voltage across a load by the current flowing through it.

2

Derive the formula relating power to current and resistance

P = I^2 R

By substituting

V = I \times R

from Ohm's Law into

P = V \times I

, power is expressed in terms of current squared times resistance.

3

Derive the formula relating power to voltage and resistance

P = \frac{V^2}{R}

By substituting

I = \frac{V}{R}

from Ohm's Law into

P = V \times I

, power is expressed in terms of voltage squared divided by resistance.

4

Identify the standard unit and definition of power

1\text{ W} = 1\text{ J/s}

Power measures the rate of doing work or dissipating energy, where one watt equals one joule per second.

Anahtar Kavram

Watt's Law and Electrical Power Formulas

Tahmini Süre:45s

Soru 110Soru →

An electronics technician observes that inside an uncooled avionics chassis, a pure silicon diode demonstrates a significant decrease in internal resistance as ambient temperature climbs, whereas surrounding standard copper wiring exhibits increased resistance. What is the primary atomic mechanism that causes the electrical conductivity of an intrinsic semiconductor to increase as temperature rises?

Thermal expansion forces the four valence electrons to tightly lock into covalent bonds, preventing atomic vibration and allowing current to pass unimpeded.

Thermal energy breaks covalent bonds within the crystal lattice, exciting valence electrons across the forbidden band gap into the conduction band to generate free electron-hole pairs.

Increased temperature accelerates the drift velocity of preexisting free electrons, eliminating collisions between charge carriers and the stationary nucleus.

The semiconductor atom's outer shell absorbs free electrons from neighboring insulator jackets, increasing the net negative charge and converting the material into an active voltage source.

Cevabı ve açıklamayı göster

Cevap: Thermal energy breaks covalent bonds within the crystal lattice, exciting valence electrons across the forbidden band gap into the conduction band to generate free electron-hole pairs.

Cevap

Thermal energy excites valence electrons across the forbidden energy gap into the conduction band, creating free electron-hole pairs that increase conductivity.

In intrinsic semiconductors such as pure silicon, the valence band is nearly full and the conduction band is nearly empty at low temperatures, separated by a relatively narrow forbidden band gap (approximately 1.1 eV for silicon). When temperature rises, thermal agitation provides sufficient kinetic energy to break covalent bonds, exciting valence electrons across this gap into the conduction band. This process generates both free conduction electrons and mobile holes, dramatically increasing the carrier density and lowering the material's electrical resistance (negative temperature coefficient of resistance).

Adım Adım Çözüm

1

Analyze the valence electron structure of intrinsic semiconductors (Group IV elements like silicon and germanium).

Silicon has four valence electrons that form covalent bonds with four adjacent atoms in a crystalline lattice, leaving virtually zero free electrons at absolute zero.

Understanding the baseline atomic bonding of semiconductors is essential to distinguish them from metallic conductors with abundant free electrons.

2

Evaluate the effect of thermal energy on semiconductor covalent bonds versus metallic conductors.

In metals, heating increases lattice vibrations, causing greater electron scattering and higher resistance (positive temperature coefficient). In semiconductors, heat supplies energy to break covalent bonds, promoting electrons across the narrow forbidden band gap into the conduction band.

This explains the negative temperature coefficient of resistance characteristic of intrinsic semiconductors.

3

Identify the resulting charge carriers and impact on electrical conductivity.

Each liberated electron creates a free negative carrier in the conduction band and leaves behind a positive vacancy (hole) in the valence band, drastically increasing total charge carrier concentration and reducing resistance.

Conductivity is directly proportional to the concentration of mobile charge carriers.

Anahtar Kavram

Semiconductor Temperature Coefficient and Electron-Hole Pair Generation

Tahmini Süre:1m 30s

Soru 111Soru →

An automotive technician tests a fuel level sensor module connected to a $12\text{ V}$ direct current (DC) supply. An in-line digital multimeter measures a steady current flow of $15\text{ mA}$ through the module. What is the electrical resistance of the sensor module?

0.8\text{ }\Omega

1.25\text{ }\Omega

800\text{ }\Omega

180\text{ }\Omega

Cevabı ve açıklamayı göster

Cevap: $800\text{ }\Omega$

Cevap

The electrical resistance of the sensor module is

800\text{ }\Omega

.

According to Ohm's law, resistance equals voltage divided by current (

R = \frac{V}{I}

). Converting

15\text{ mA}

to amperes gives

0.015\text{ A}

. Dividing

12\text{ V}

by

0.015\text{ A}

yields

800\text{ }\Omega

.

Adım Adım Çözüm

1

Convert the measured current from milliamperes (mA) to the base SI unit amperes (A).

I = 15\text{ mA} = 15 \times 10^{-3}\text{ A} = 0.015\text{ A}

Standard electrical formulas require quantities in base units (volts, amperes, ohms).

2

State Ohm's law rearranged to solve for resistance (

R

).

R = \frac{V}{I}

Resistance equals electromotive force (voltage) divided by current flow.

3

Substitute the given values into the formula and calculate the resistance.

R = \frac{12\text{ V}}{0.015\text{ A}} = \frac{12000}{15}\text{ }\Omega = 800\text{ }\Omega

Dividing

12\text{ V}

by

0.015\text{ A}

yields the total circuit resistance in ohms.

Anahtar Kavram

Ohm's Law (

V = I \times R

) defines the relationship between voltage, current, and resistance in a DC circuit.

Tahmini Süre:45s

Soru 112Soru →

An electrical technician wants to reduce the electrical resistance of a standard copper wire run without changing the metal type or operating temperature. Which of the following modifications will decrease the resistance of the wire?

Increasing the total length of the wire

Increasing the cross-sectional area of the wire

Operating the wire at a significantly elevated temperature

Selecting a wire with a smaller circular diameter

Cevabı ve açıklamayı göster

Cevap: Increasing the cross-sectional area of the wire

Cevap

Increasing the cross-sectional area of the wire decreases its electrical resistance.

Electrical resistance in a conductor is inversely proportional to its cross-sectional area (

R = \rho \frac{L}{A}

). Increasing the thickness or cross-sectional area provides more conductive pathways for free electrons, thereby lowering the total resistance.

Adım Adım Çözüm

1

Recall the fundamental physical relationship between conductor dimensions and electrical resistance

R = \rho \frac{L}{A}

, where

R

is resistance,

\rho

is material resistivity,

L

is conductor length, and

A

is cross-sectional area

This formula defines how physical geometry directly influences opposition to electron flow.

2

Analyze how changing the cross-sectional area (

A

) impacts resistance (

R

)

Because cross-sectional area (

A

) is in the denominator, resistance is inversely proportional to area (

R \propto \frac{1}{A}

)

Increasing the area (

A

) reduces the calculated resistance (

R

), allowing electrons to flow more easily.

Anahtar Kavram

Physical factors governing conductor resistance

Tahmini Süre:45s

Soru 113Soru →

A direct-current (DC) ventilation blower operates on a $28\text{ V}$ aircraft electrical bus and draws a steady current of $5\text{ A}$ . How many watts ( $\text{W}$ ) of electrical power are consumed by the blower?

Cevabı ve açıklamayı göster

Cevap: 140

Cevap

The power consumed by the blower is

140\text{ W}

.

According to Watt's Law, electrical power (

P

) dissipated by a direct-current device equals the product of the applied voltage (

V

) and the current (

I

). Multiplying

28\text{ V}

by

5\text{ A}

gives

140\text{ W}

.

Adım Adım Çözüm

1

Identify the known electrical quantities given in the scenario.

Voltage

V = 28\text{ V}

and Current

I = 5\text{ A}

.

Identifying the known parameters determines which form of Watt's Law to use.

2

Apply the fundamental Watt's Law formula for electrical power (

P = V \times I

).

P = 28\text{ V} \times 5\text{ A} = 140\text{ W}

.

Electrical power in a direct-current circuit is calculated by multiplying the potential difference across the load by the current flowing through it.

Anahtar Kavram

Watt's Law for DC Power (

P = V \times I

)

Tahmini Süre:45s

Soru 114Soru →

A direct current (DC) cooling fan in an electronics enclosure operates at a voltage of $24\text{ V}$ and draws a current of $1.5\text{ A}$ . What is the total electrical power consumed by the fan?

16\text{ W}

25.5\text{ W}

36\text{ W}

54\text{ W}

Cevabı ve açıklamayı göster

Cevap: $36\text{ W}$

Cevap

36\text{ W}

According to Watt's Law, electrical power in a DC circuit is determined by multiplying the voltage by the current (

P = V \times I

). Multiplying

24\text{ V}

by

1.5\text{ A}

results in

36\text{ W}

of power dissipation.

Adım Adım Çözüm

1

Identify the given electrical quantities and the appropriate Watt's Law formula.

Voltage

V = 24\text{ V}

, Current

I = 1.5\text{ A}

, Formula:

P = V \times I

Electrical power in a DC circuit is directly defined as the product of electromotive force (voltage) and current.

2

Substitute the values into the formula and calculate the power.

P = 24\text{ V} \times 1.5\text{ A} = 36\text{ W}

Multiplying

24

by

1.5

gives

36

, with the standard unit of power being watts (W).

Anahtar Kavram

Watt's Law calculates electrical power (

P

) as the product of voltage (

V

) and current (

I

), expressed as

P = V \times I

.

Tahmini Süre:45s

Soru 115Soru →

When comparing two electrical wires of identical length, diameter, and temperature, which material property determines which wire has lower electrical resistance?

Applied voltage

Resistivity

Dielectric strength

Inductance

Cevabı ve açıklamayı göster

Cevap: Resistivity

Cevap

Resistivity is the material property that determines the electrical resistance of equal-dimensioned conductors.

Resistivity (represented by

\rho

) is an intrinsic physical property of a material that measures its natural opposition to electric current flow. According to the formula

R = \rho \frac{L}{A}

, when two conductors share identical length (

L

) and cross-sectional area (

A

) at constant temperature, the wire made of a material with lower resistivity will have lower total electrical resistance.

Adım Adım Çözüm

1

Apply the fundamental formula for conductor resistance:

R = \rho \frac{L}{A}

.

Total resistance (

R

) is directly proportional to conductor length (

L

), inversely proportional to cross-sectional area (

A

), and directly proportional to resistivity (

\rho

).

Because length, diameter (area), and temperature are held constant between the two wires, any difference in total resistance is strictly governed by the material's resistivity.

2

Identify the property representing the material's specific opposition to current.

Resistivity (

\rho

) is the intrinsic characteristic of the substance.

A material with lower resistivity (such as copper compared to iron) will always yield a lower resistance when shaped into identical physical dimensions.

Anahtar Kavram

Resistance and Resistivity

Tahmini Süre:45s

Soru 116Soru →

A piece of copper hookup wire with a length of $15\text{ m}$ has an electrical resistance of $0.6\ \Omega$ . If the wire is replaced with a $45\text{ m}$ piece of the exact same wire type and gauge at the same temperature, what is the resistance of the new wire in ohms ( $\Omega$ )?

Cevabı ve açıklamayı göster

Cevap: 1.8

Cevap

1.8 \Omega

According to the fundamental resistance relationship

R = \rho \frac{L}{A}

, resistance is directly proportional to the length

L

of the conductor when resistivity

\rho

and cross-sectional area

A

remain unchanged. Tripling the wire length from

15\text{ m}

to

45\text{ m}

multiplies the resistance by a factor of 3, resulting in

0.6\ \Omega \times 3 = 1.8\ \Omega

.

Adım Adım Çözüm

1

Calculate the proportional change in conductor length.

The new length is 3 times the original length (

45\text{ m} \div 15\text{ m} = 3

).

Identifying the scaling factor allows direct application of the resistance formula.

2

Apply the direct proportionality between conductor length and electrical resistance (

R \propto L

).

R_{\text{new}} = R_{\text{old}} \times 3 = 0.6\ \Omega \times 3 = 1.8\ \Omega

.

Since material resistivity (

\rho

) and cross-sectional area (

A

) are held constant, tripling the length triples the total resistance.

Anahtar Kavram

The electrical resistance of a uniform conductor is directly proportional to its length (

R = \rho \frac{L}{A}

).

Tahmini Süre:45s

Soru 117Soru →

In an external circuit connected to a direct-current (DC) power source, electron flow theory states that negative charge carriers travel from the positive terminal to the negative terminal.

Doğru

Yanlış

Cevabı ve açıklamayı göster

Cevap: False

Cevap

False

Electron flow theory describes the physical movement of negatively charged electrons, which travel from the negative terminal through the external circuit load toward the positive terminal. Traveling from positive to negative describes conventional current flow.

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1

Identify the electrical current model referenced in the statement.

The statement explicitly cites 'electron flow theory' in an external circuit.

Electronics distinguishes between electron flow theory and conventional current flow theory.

2

Determine the physical direction of electrons based on fundamental electrostatic laws.

Electrons possess a negative charge, causing them to be repelled by the negative terminal and drawn toward the positive terminal.

Like charges repel each other while opposite charges attract.

3

Evaluate the accuracy of the statement's claimed direction.

Movement from positive to negative defines conventional current, making the claim regarding electron flow theory false.

Electron flow moves from negative to positive externally.

Anahtar Kavram

Direction of Electron Flow vs. Conventional Current

Tahmini Süre:35s

Soru 118Soru →

A marine communications transceiver utilizes a direct current (DC) bias network. A voltmeter connected across a fixed $2.5\text{ k}\Omega$ resistor measures a steady voltage drop of $15\text{ V}$ . What is the current flowing through this resistor?

37.5\text{ mA}

167\text{ mA}

6\text{ mA}

0.6\text{ mA}

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Cevap: $6\text{ mA}$

Cevap

The current flowing through the resistor is

6\text{ mA}

.

According to Ohm's law, current equals voltage divided by resistance (

I = V / R

). Dividing

15\text{ V}

by

2.5\text{ k}\Omega

(

2500\text{ }\Omega

) yields

0.006\text{ A}

, which converts directly to

6\text{ mA}

.

Adım Adım Çözüm

1

Convert the given resistance from kilo-ohms to fundamental SI units (ohms).

R = 2.5\text{ k}\Omega = 2.5 \times 10^3\text{ }\Omega = 2500\text{ }\Omega

Standard calculations in Ohm's law require values in fundamental units (volts, amperes, ohms).

2

Apply Ohm's law formula to solve for current (

I = V / R

).

I = \frac{15\text{ V}}{2500\text{ }\Omega} = 0.006\text{ A}

Current is directly proportional to voltage and inversely proportional to resistance.

3

Convert the resulting current from amperes to milliamperes.

0.006\text{ A} = 0.006 \times 1000\text{ mA} = 6\text{ mA}

Matching the standard unit formatting in electronic measurement options.

Anahtar Kavram

Ohm's Law expresses the fundamental relationship between voltage, current, and resistance in a DC circuit (

I = V / R

).

Tahmini Süre:1m 0s

Soru 119Soru →

An aircraft technician monitors a steady direct-current (DC) sensor loop and determines that $24\text{ coulombs}$ of charge pass through a test conductor in $6\text{ seconds}$ . What is the current in this conductor, and in which direction do the electrons physically drift?

4\text{ A}

, drifting from the positive terminal toward the negative terminal

144\text{ A}

, drifting from the negative terminal toward the positive terminal

4\text{ A}

, drifting from the negative terminal toward the positive terminal

4\text{ A}

, oscillating back and forth continuously without net forward drift

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Cevap: $4\text{ A}$ , drifting from the negative terminal toward the positive terminal

Cevap

4\text{ A}

, drifting from the negative terminal toward the positive terminal

Electric current is the time rate of charge transfer (

I = \frac{Q}{t} = \frac{24\text{ C}}{6\text{ s}} = 4\text{ A}

). In electron flow theory, negatively charged electrons are repelled by the negative terminal and flow through the external circuit toward the positive terminal.

Adım Adım Çözüm

1

Calculate the magnitude of the electric current using the relationship between charge, current, and time

I = \frac{Q}{t} = \frac{24\text{ C}}{6\text{ s}} = 4\text{ A}

Electric current is defined as the rate at which charge flows past a point in a conductor per unit time.

2

Determine the physical direction of electron flow in a direct-current circuit

Electrons move from negative potential toward positive potential.

Electrons carry a negative charge and are repelled by the negative terminal and attracted toward the positive terminal.

Anahtar Kavram

Electric current definition (

I = \frac{Q}{t}

) and physical electron drift direction in direct-current circuits

Tahmini Süre:45s

Soru 120Soru →

A ceramic load resistor in a direct-current (DC) circuit has a resistance of $20\ \Omega$ and carries a steady current of $2\text{ A}$ . What is the total electrical power dissipated by this resistor?

40\text{ W}

80\text{ W}

10\text{ W}

800\text{ W}

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Cevap: $80\text{ W}$

Cevap

The total electrical power dissipated by the resistor is

80\text{ W}

.

According to Watt's Law, when current (

I

) and resistance (

R

) are known, electrical power is calculated using the formula

P = I^2 R

. Substituting

I = 2\text{ A}

and

R = 20\ \Omega

gives

P = (2\text{ A})^2 \times 20\ \Omega = 4 \times 20 = 80\text{ W}

.

Adım Adım Çözüm

1

Identify the given electrical values and select the appropriate form of Watt's Law.

Given: current

I = 2\text{ A}

, resistance

R = 20\ \Omega

. Formula:

P = I^2 R

.

When current and resistance are known, the power dissipated is calculated using

P = I^2 R

.

2

Square the current value.

I^2 = (2\text{ A})^2 = 4\text{ A}^2

.

Watt's Law requires current to be squared before multiplying by resistance.

3

Multiply the squared current by the resistance to calculate power in watts.

P = 4\text{ A}^2 \times 20\ \Omega = 80\text{ W}

.

Multiplying amperes squared by ohms yields power in watts.

Anahtar Kavram

Calculating electrical power from current and resistance using Watt's Law (

P = I^2 R

)

Tahmini Süre:45s

Basic Electrical Concepts

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