Electricity and Magnetism Practice Questions — Armed Services Vocational Aptitude Battery (ASVAB)

Question 1Question →

Understanding magnetic behaviors and electromagnetic interactions is fundamental in physical science. Match each magnetic concept on the left with its correct scientific description on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Ferromagnetic substance matches the material strongly attracted to magnets and easily magnetized; Magnetic domain matches the microscopic region where atomic magnetic fields are aligned; Magnetic field lines match the lines of force mapping direction and strength from north to south; and Electromagnetic induction matches the process of generating an electric current via a changing magnetic field.

Each physical concept is paired with its precise scientific description: ferromagnetic substances describe materials like iron and nickel that exhibit strong magnetic attraction; magnetic domains are the microscopic aligned clusters of atomic dipoles; magnetic field lines map the invisible field geometry from north to south; and electromagnetic induction refers to current generation induced by a changing magnetic environment.

Step-by-Step Solution

1

Identify the definition of a ferromagnetic substance

Matches the description of a material such as iron or nickel that is strongly attracted to magnets and can be magnetized

Ferromagnetism is the basic mechanism by which certain materials form permanent magnets or are attracted to magnets.

2

Identify the definition of a magnetic domain

Matches the description of a microscopic region within a solid where atomic magnetic fields are aligned

Domains are localized zones of uniform magnetic orientation within ferromagnetic materials.

3

Identify the definition of magnetic field lines

Matches the description of continuous lines of force emerging from north and entering south to indicate direction and strength

Field lines visually communicate the direction of the magnetic force and its magnitude through line spacing.

4

Identify the definition of electromagnetic induction

Matches the description of the process of generating an electric current in a conductor via a changing magnetic field

Relative movement between a magnetic field and a conductor produces an induced current.

Key Concept

Core concepts of magnetism, magnetic domains, field mapping, and electromagnetic induction

Estimated Time:1m 0s

Question 2Question →

An electrical circuit in an automated test bench connects a $24\text{ V}$ direct-current power supply to two $12\,\Omega$ heating elements arranged in parallel. What is the total electric current delivered by the power supply to the entire circuit?

1\text{ A}

4\text{ A}

2\text{ A}

8\text{ A}

Show answer & explanation

Answer: $4\text{ A}$

Answer

4\text{ A}

In a parallel circuit with two identical

12\,\Omega

loads, the total equivalent resistance is halved to

6\,\Omega

. By Ohm's law (

I = \frac{V}{R}

), the total current drawn from the

24\text{ V}

source is

\frac{24\text{ V}}{6\,\Omega} = 4\text{ A}

. Alternatively, each branch draws

\frac{24\text{ V}}{12\,\Omega} = 2\text{ A}

, yielding a total current of

2\text{ A} + 2\text{ A} = 4\text{ A}

.

Step-by-Step Solution

1

Calculate the equivalent resistance of the two identical resistors connected in parallel.

R_{\text{eq}} = \frac{12\,\Omega}{2} = 6\,\Omega

When identical resistors are in parallel, the equivalent resistance equals the resistance of one branch divided by the total number of branches.

2

Apply Ohm's law (

I = \frac{V}{R_{\text{eq}}}

) using the total source voltage and equivalent resistance.

I_{\text{total}} = \frac{24\text{ V}}{6\,\Omega} = 4\text{ A}

Ohm's law defines the relationship between total circuit voltage, equivalent resistance, and total current.

Key Concept

Parallel circuit resistance and Ohm's law

Estimated Time:1m 0s

Question 3Question →

A ceramic space heater is connected to a standard $120\text{ V}$ electrical outlet. If the heating element has an internal resistance of $15\,\Omega$ , what is the electric current flowing through the circuit, in amperes ( $\text{A}$ )?

Show answer & explanation

Answer: 8

Answer

8 A

According to Ohm's Law (

V = IR

), the electric current (

I

) flowing through a circuit is found by dividing the potential difference (

V

) by the resistance (

R

). Dividing

120\text{ V}

by

15\,\Omega

gives an electric current of

8\text{ A}

.

Step-by-Step Solution

1

Identify the given electrical values from the problem statement.

Voltage

V = 120\text{ V}

and resistance

R = 15\,\Omega

.

Determining known quantities is required to choose the appropriate formula.

2

State Ohm's Law and isolate current (

I

).

I = \frac{V}{R}

Ohm's Law governs the relationship between potential difference, current, and resistance in an electrical circuit.

3

Divide voltage by resistance to calculate the current in amperes.

I = \frac{120\text{ V}}{15\,\Omega} = 8\text{ A}

Carrying out the arithmetic yields the resulting current in amperes.

Key Concept

Ohm's Law (

V = IR

) defines the relationship among voltage, current, and resistance, where current is directly proportional to voltage and inversely proportional to resistance.

Estimated Time:1m 0s

Question 4Question →

An emergency backup lighting system connects three identical $15\,\Omega$ indicator lamps in series across a $45\text{ V}$ direct-current power source. What is the electric current flowing through each lamp?

0.33\text{ A}

3.0\text{ A}

1.0\text{ A}

9.0\text{ A}

Show answer & explanation

Answer: $1.0\text{ A}$

Answer

1.0\text{ A}

In a series circuit, the total electrical resistance is the sum of all individual resistances in the path:

R_{\text{total}} = 15\,\Omega + 15\,\Omega + 15\,\Omega = 45\,\Omega

. Applying Ohm's law (

I = \frac{V}{R}

), the current drawn from the

45\text{ V}

source is

I = \frac{45\text{ V}}{45\,\Omega} = 1.0\text{ A}

. In any series circuit, the electric current is identical at every point, meaning exactly

1.0\text{ A}

flows through each lamp.

Step-by-Step Solution

1

Calculate the total equivalent resistance of the series circuit.

R_{\text{total}} = 15\,\Omega + 15\,\Omega + 15\,\Omega = 45\,\Omega

In a series circuit, the total electrical resistance equals the direct sum of all individual resistances.

2

Apply Ohm's law to determine the total circuit current.

I = \frac{V}{R_{\text{total}}} = \frac{45\text{ V}}{45\,\Omega} = 1.0\text{ A}

Current is calculated by dividing total source voltage by the total resistance of the circuit.

3

Determine the current flowing through each individual lamp.

I_{\text{lamp}} = 1.0\text{ A}

Because there is only one continuous path for electrical charge in a series circuit, the current is uniform through all components.

Key Concept

Ohm's law and total resistance in series circuits

Estimated Time:1m 0s

Question 5Question →

Electrical circuits and power distribution systems utilize specialized components to regulate, convert, and protect electrical energy. Which functional description correctly matches each electrical component?

Click a left item, then click its matching right item

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Answer

The correct pairings match Fuse with interrupting excessive current by melting a sacrificial strip, Transformer with altering alternating-current voltage levels through electromagnetic induction, Capacitor with storing separated electric charge across an insulating dielectric layer, and Diode with restricting current flow primarily to a single direction.

Each component is correctly paired with its defining physical mechanism: a fuse provides overcurrent protection by melting its internal element; a transformer modulates AC voltage via mutual electromagnetic induction; a capacitor accumulates electrostatic charge across separated plates; and a diode rectifies or guides current in a single direction.

Step-by-Step Solution

1

Identify the protective mechanism of a fuse.

A fuse contains a thin wire designed to melt under overcurrent conditions, matching the description of interrupting excessive current by melting a sacrificial strip.

Fuses protect wiring and equipment from dangerous current overloads and short circuits.

2

Identify the electromagnetic function of a transformer.

A transformer transfers energy between AC circuits through mutual magnetic flux, matching the description of altering AC voltage levels through electromagnetic induction.

Transformers rely on changing magnetic fields produced by alternating current to induce voltage across windings.

3

Identify the electrostatic storage mechanism of a capacitor.

A capacitor holds electrostatic charge on opposing plates separated by a dielectric, matching the description of accumulating and storing separated electric charge.

Capacitors maintain potential difference by holding static charge rather than dissipating or converting it.

4

Identify the unidirectional conducting property of a diode.

A diode conducts forward-bias current while blocking reverse-bias current, matching the description of restricting current flow to a single direction.

Diodes are fundamental semiconductor components used in rectification and polarity protection.

Key Concept

Functional characteristics and operating principles of fundamental electrical circuit components

Estimated Time:1m 0s

Question 6Question →

A remote weather-monitoring station is powered by a $36\text{ V}$ direct-current solar battery bank. Two identical communication transmitters are connected in parallel across the power terminals. If the monitoring station draws a total current of $4\text{ A}$ when both transmitters are operating simultaneously, what is the electrical resistance of each individual transmitter?

9\,\Omega

4.5\,\Omega

18\,\Omega

180\,\Omega

Show answer & explanation

Answer: $18\,\Omega$

Answer

The electrical resistance of each individual transmitter is

18\,\Omega

.

In a parallel circuit, each identical branch draws an equal share of the total current. With a total current of

4\text{ A}

split evenly across two identical paths, each transmitter draws

2\text{ A}

. Applying Ohm's law (

R = \frac{V}{I}

) across one branch with the full

36\text{ V}

potential difference yields

R = \frac{36\text{ V}}{2\text{ A}} = 18\,\Omega

.

Step-by-Step Solution

1

Calculate the total equivalent resistance of the parallel circuit using Ohm's Law.

R_{\text{eq}} = \frac{V}{I_{\text{total}}} = \frac{36\text{ V}}{4\text{ A}} = 9\,\Omega

The total resistance of the entire circuit relates the total supply voltage to the total current drawn from the battery bank.

2

Determine the resistance of each individual transmitter from the parallel combination formula.

\frac{1}{R_{\text{eq}}} = \frac{1}{R} + \frac{1}{R} = \frac{2}{R} \implies R = 2 \times R_{\text{eq}} = 2 \times 9\,\Omega = 18\,\Omega

When two identical resistors are connected in parallel, their equivalent resistance is equal to half the resistance of a single component.

Key Concept

Ohm's law and equivalent resistance in parallel circuits

Alternative Method

Determine the current per branch directly: because the two transmitters are identical and in parallel across the

36\text{ V}

source, each receives the full supply voltage and carries half the total current (

I_{\text{branch}} = \frac{4\text{ A}}{2} = 2\text{ A}

). Then apply Ohm's law directly to a single branch:

R = \frac{V}{I_{\text{branch}}} = \frac{36\text{ V}}{2\text{ A}} = 18\,\Omega

.

Estimated Time:1m 0s

Question 7Question →

A workshop exhaust fan is connected to a $120\text{ V}$ power supply and consumes $480\text{ W}$ of electric power during normal operation. What is the effective electrical resistance of the fan motor, in ohms ( $\Omega$ )?

Show answer & explanation

Answer: 30

Answer

The effective electrical resistance of the fan motor is

30\,\Omega

.

To find the resistance from voltage and power, determine the current using

I = \frac{P}{V} = \frac{480\text{ W}}{120\text{ V}} = 4\text{ A}

, then use Ohm's law

R = \frac{V}{I} = \frac{120\text{ V}}{4\text{ A}} = 30\,\Omega

. Alternatively, using

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

yields

\frac{120^2}{480} = \frac{14400}{480} = 30\,\Omega

.

Step-by-Step Solution

1

Calculate the electric current flowing through the fan motor using the electrical power formula

P = V \times I

.

I = \frac{P}{V} = \frac{480\text{ W}}{120\text{ V}} = 4\text{ A}

Electric power equals the product of voltage and current, so dividing total wattage by applied voltage determines circuit current.

2

Calculate the resistance using Ohm's law rearranged as

R = \frac{V}{I}

.

R = \frac{120\text{ V}}{4\text{ A}} = 30\,\Omega

Resistance represents the opposition to current flow and is found by dividing the applied voltage by the circuit current.

Key Concept

Relationship between electrical power (

P = IV

) and Ohm's law (

V = IR

)

Estimated Time:1m 0s

Question 8Question →

In an industrial facility, three identical light fixtures are connected in parallel across a constant $120\text{ V}$ electrical line. If one of the light fixtures burns out and creates an open circuit in its branch, what will happen to the remaining light fixtures and the total current drawn from the line?

All remaining fixtures go out immediately, and the total current drawn from the line drops to zero.

The remaining fixtures stay lit at the same brightness, and the total current drawn from the line decreases.

The remaining fixtures glow noticeably brighter, and the total current drawn from the line increases.

The remaining fixtures become dimmer, while the total current drawn from the line remains unchanged.

Show answer & explanation

Answer: The remaining fixtures stay lit at the same brightness, and the total current drawn from the line decreases.

Answer

The remaining fixtures stay lit at the same brightness, and the total current drawn from the line decreases.

In a parallel circuit, each device is connected across the full source voltage independently. When one fixture burns out, the voltage across the remaining fixtures remains at

120\text{ V}

, so their current and brightness stay the same. However, because the total current is the sum of the branch currents (

I_{\text{total}} = I_1 + I_2 + I_3

), losing one branch reduces the total current supplied by the line from three branch currents down to two.

Step-by-Step Solution

1

Analyze voltage across individual branches in a parallel circuit

Each remaining fixture continues to experience the full

120\text{ V}

line voltage.

In a parallel circuit, every branch is connected directly across the power source, so removing or opening one branch does not alter the voltage applied to the others.

2

Determine current and power dissipation for each remaining fixture

Individual current

I = \frac{V}{R}

and power

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

remain constant, keeping brightness unchanged.

Since both the resistance of each remaining fixture and the supply voltage remain unchanged, the power output of each active lamp does not change.

3

Calculate the effect on total circuit current

Total current drops from

I_{\text{total}} = 3I_{\text{branch}}

to

I_{\text{total}} = 2I_{\text{branch}}

.

Total current in a parallel circuit is the sum of the individual branch currents (

I_{\text{total}} = I_1 + I_2 + I_3

). When one branch opens, its current drops to zero, reducing the total current drawn from the supply.

Key Concept

Parallel Circuit Branch Independence and Current Summation

Estimated Time:1m 0s

Question 9Question →

In the analysis of direct-current electrical circuits, fundamental physical quantities define how electrical energy is stored, transported, and dissipated. Match each electrical quantity on the left with its correct physical definition on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Electric Current matches 'The rate at which electric charge flows through a cross-sectional area of a conductor over time'; Voltage (Electric Potential Difference) matches 'The amount of electric potential energy delivered or work done per unit of electric charge'; Electrical Resistance matches 'The measure of a material's opposition to the passage of electric charge'; Electrical Power matches 'The rate at which electrical energy is transferred, converted, or dissipated per unit of time'.

Each term corresponds directly to its foundational physical definition in electromagnetism: Electric Current is the rate of charge flow (

I = \frac{\Delta Q}{\Delta t}

), Voltage is the work/energy per unit charge (

V = \frac{W}{Q}

), Resistance is the opposition to charge movement (

R = \frac{V}{I}

), and Electrical Power is the time rate of total energy transfer (

P = VI

).

Step-by-Step Solution

1

Determine the physical definition of Electric Current.

Electric current is the flow of electric charge per unit time (

I = \frac{\Delta Q}{\Delta t}

), which matches 'The rate at which electric charge flows through a cross-sectional area of a conductor over time'.

Current measures how many coulombs of charge pass through a point each second.

2

Determine the physical definition of Voltage (Electric Potential Difference).

Voltage is the potential energy difference per unit charge (

V = \frac{W}{Q}

), which matches 'The amount of electric potential energy delivered or work done per unit of electric charge'.

Voltage represents the electrical 'push' or work done to move a unit charge between two points.

3

Determine the physical definition of Electrical Resistance.

Resistance describes the opposition encountered by flowing charge (

R = \frac{V}{I}

), which matches 'The measure of a material's opposition to the passage of electric charge'.

Resistance impedes electric current and creates a potential drop across a circuit component.

4

Determine the physical definition of Electrical Power.

Electrical power is the rate of energy transformation or consumption (

P = \frac{\Delta E}{\Delta t} = VI

), which matches 'The rate at which electrical energy is transferred, converted, or dissipated per unit of time'.

Power quantifies how rapidly electrical potential energy is converted into thermal energy, light, or mechanical work.

Key Concept

Fundamental electrical circuit quantities, their standard physical definitions, and underlying unit relationships

Estimated Time:1m 0s

Question 10Question →

Match each electromagnetic device or physical phenomenon on the left with its corresponding fundamental mechanism and energy interaction on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Electromagnetic induction matches the generation of an electromotive force via varying magnetic flux; magnetic torque in a motor matches the Lorentz force acting on current-carrying conductors; Joule heating matches the conversion of electrical energy into thermal dissipation through lattice collisions; and capacitor storage matches the retention of potential energy in an electric field across an insulating dielectric.

Each electromagnetic concept correctly corresponds to its underlying physical law: electromagnetic induction generates voltage from changing magnetic flux, motor action generates mechanical torque from magnetic forces on current, resistive heating results from microscopic electron collisions yielding thermal dissipation, and capacitors store potential energy in the electric field between separated charges.

Step-by-Step Solution

1

Analyze the operational principle of generators versus motors.

Generators convert mechanical work to electricity via changing magnetic flux (induction), whereas motors convert electrical current in a magnetic field to mechanical torque (Lorentz force).

Differentiating between motor action (electrical-to-mechanical) and generator action (mechanical-to-electrical) prevents confusing input and output energy forms.

2

Analyze energy dissipation in resistive components.

Resistive conduction dissipates energy thermally as moving charge carriers collide with conductor ions.

Ohmic resistance transforms electric potential energy irreversibly into internal thermal energy.

3

Analyze static field storage in reactive capacitive components.

Capacitors hold charge statically across a dielectric boundary, storing energy within an electric field rather than dissipating it or relying on continuous charge flow.

Capacitive storage is electrostatic and reversible, contrasting with resistive thermal dissipation and magnetic induction.

Key Concept

Fundamental principles of electromagnetism, circuit components, and electromechanical energy conversions

Estimated Time:1m 30s

Question 11Question →

A direct-current circuit is powered by a $12\text{ V}$ battery connected in series with a $3\,\Omega$ resistor, followed by two $6\,\Omega$ resistors connected in parallel with each other. If one of the $6\,\Omega$ parallel resistors burns out and creates an open circuit, what is the total electrical power consumed by the remaining active circuit?

24\text{ W}

8\text{ W}

16\text{ W}

48\text{ W}

Show answer & explanation

Answer: $16\text{ W}$

Answer

16\text{ W}

When one of the parallel

6\,\Omega

resistors opens, the parallel network is reduced to the single remaining

6\,\Omega

resistor. This resistor is in series with the

3\,\Omega

resistor, giving a total equivalent resistance of

R = 3\,\Omega + 6\,\Omega = 9\,\Omega

. Applying the power formula

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

with a

12\text{ V}

battery gives

P = \frac{144}{9} = 16\text{ W}

.

Step-by-Step Solution

1

Determine the new circuit configuration after component failure

A single

3\,\Omega

resistor in series with the remaining

6\,\Omega

resistor

When one parallel branch burns out into an open circuit, no current flows through that branch, leaving the remaining parallel resistor in direct series with the first resistor.

2

Calculate the total equivalent resistance (

R_{\text{total}}

)

R_{\text{total}} = 3\,\Omega + 6\,\Omega = 9\,\Omega

Resistances in series add directly together.

3

Calculate total electrical power using the formula

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

P = \frac{(12\text{ V})^2}{9\,\Omega} = \frac{144}{9} = 16\text{ W}

Electrical power is directly proportional to the square of the source voltage and inversely proportional to the total equivalent resistance.

Key Concept

Series-Parallel Circuit Analysis and Electrical Power Calculation

Estimated Time:1m 30s

Question 12Question →

In basic direct-current circuits, various fundamental electrical quantities describe the flow and use of electric energy. Match each electrical quantity on the left with its correct physical definition and standard unit on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Voltage matches the electrical potential difference driving charge (volts); Current matches the rate of charge flow (amperes); Resistance matches the opposition to current flow (ohms); Electrical Power matches the rate of energy transfer (watts).

Each electrical quantity is correctly matched to its standard SI unit and underlying physical definition based on Ohm's law and electrical power principles.

Step-by-Step Solution

1

Identify the definitions and units for potential difference and charge flow.

Voltage provides the electrical push measured in volts (

\text{V}

), while Current represents the flow rate of charge measured in amperes (

\text{A}

).

These are the two driving and kinematic parameters of an active circuit.

2

Identify the definitions and units for circuit opposition and energy rate.

Resistance opposes current flow and is measured in ohms (

\Omega

), while Electrical Power is the energy conversion rate measured in watts (

\text{W}

).

These relate the load characteristics and total work rate in the circuit.

Key Concept

Fundamental electrical properties, units of measurement, and definitions in direct-current circuits.

Estimated Time:45s

Question 13Question →

A string of decorative holiday lights is designed such that removing a single bulb causes all the other bulbs on the strand to go out immediately. Which type of electrical circuit does this light strand represent?

A parallel circuit, because each component operates on an independent branch

A series circuit, because all components share a single continuous path for electric current

A parallel circuit, because current stops dividing among multiple pathways

A short circuit, because electrical resistance in the wire drops to zero

Show answer & explanation

Answer: A series circuit, because all components share a single continuous path for electric current

Answer

A series circuit, because all components share a single continuous path for electric current

In a series circuit, all electrical loads are connected end-to-end along a single continuous path. Because electric current must travel through each component sequentially, removing or burning out any one bulb breaks the loop, creating an open circuit that immediately turns off all remaining bulbs.

Step-by-Step Solution

1

Identify the pathway configuration of the electrical components in the circuit

The circuit contains only one continuous conducting path connecting every bulb in sequence.

Understanding the number of paths for current flow determines whether a circuit is wired in series or in parallel.

2

Analyze the effect of removing a component on the circuit loop

Removing one bulb creates a gap (open circuit), halting the flow of charge through the entire path.

Electric current requires an uninterrupted closed loop from the power source back to the source to flow.

Key Concept

Series vs. Parallel Circuits and Current Pathways

Estimated Time:45s

Question 14Question →

A portable work light operates on a simple direct-current circuit. When switched on, an electric current of $2\text{ A}$ passes through the bulb, which has a resistance of $3\,\Omega$ . According to Ohm's law ( $V = I \times R$ ), what is the voltage supplied by the battery?

1.5\text{ V}

5\text{ V}

6\text{ V}

0.67\text{ V}

Show answer & explanation

Answer: $6\text{ V}$

Answer

The voltage supplied by the battery is

6\text{ V}

.

According to Ohm's law, voltage (

V

) equals current (

I

) multiplied by resistance (

R

). Multiplying

2\text{ A}

by

3\,\Omega

gives

6\text{ V}

.

Step-by-Step Solution

1

Identify the given electrical quantities from the problem.

Current

I = 2\text{ A}

and resistance

R = 3\,\Omega

.

Ohm's law requires current and resistance to determine voltage.

2

Apply Ohm's law formula

V = I \times R

.

V = 2\text{ A} \times 3\,\Omega = 6\text{ V}

.

Multiplying electric current by internal resistance calculates the total potential difference (voltage).

Key Concept

Ohm's law states that the electrical potential difference (voltage) across a conductor is directly proportional to the current flowing through it, given by

V = I \times R

.

Estimated Time:40s

Question 15Question →

Electromagnetic principles are applied in many common electrical machines and tools. Match each device with its primary operational function.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Electric Generator matches with converting mechanical energy to electrical energy; Electric Motor matches with converting electrical energy to mechanical rotation; Transformer matches with adjusting alternating current voltage levels; Electromagnet matches with producing a controllable magnetic field from electric current.

Each electromagnetic device corresponds directly to its defined operational function: generators convert mechanical work into electricity, motors convert electricity into mechanical rotation, transformers step AC voltage up or down, and electromagnets create temporary magnetic fields via electric current.

Step-by-Step Solution

1

Identify the energy transformation in an electric generator.

Mechanical energy is converted into electrical energy via induction.

Generators are driven by mechanical power to produce current.

2

Identify the energy transformation in an electric motor.

Electrical energy is converted into mechanical motion.

Motors consume electricity to produce physical torque and rotation.

3

Identify the primary role of a transformer in power distribution.

Voltage levels of alternating current are increased or decreased.

Transformers rely on changing magnetic flux between primary and secondary coils to adjust voltage.

4

Identify the mechanism of an electromagnet.

Current flowing through a coil creates a magnetic field.

Moving electric charges naturally produce magnetic fields around the coil.

Key Concept

Electromagnetic Devices and Energy Transformations

Estimated Time:45s

Question 16Question →

A $12\text{ V}$ direct-current car battery is connected to a circuit powering a single headlight with a resistance of $4\,\Omega$ . What is the electric current, in amperes, flowing through the headlight?

Show answer & explanation

Answer: 3

Answer

The electric current flowing through the headlight is 3 amperes.

According to Ohm's law, electric current (

I

) equals voltage (

V

) divided by resistance (

R

). Dividing a voltage of

12\text{ V}

by a resistance of

4\,\Omega

yields an electric current of

3\text{ A}

.

Step-by-Step Solution

1

Identify the relationship between voltage, current, and resistance using Ohm's law.

V = I \times R

, which rearranges to

I = \frac{V}{R}

.

Ohm's law governs the relationship between electric potential difference, current flow, and resistance in a DC circuit.

2

Substitute the given values into the formula and solve for current.

I = \frac{12\text{ V}}{4\,\Omega} = 3\text{ A}

Dividing the electromotive force (voltage) by the total circuit resistance yields the resulting electric current.

Key Concept

Ohm's Law (

V = IR

)

Electricity and Magnetism

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