FE Other Disciplines (NCEES Fundamentals of Engineering) — All Questions

What is the capacitive reactance of a 100 uF capacitor at 60 Hz? (Xc = 1/(2*pi*f*C))

• a.26.5 ohms✓
• b.377 ohms
• c.0.0377 ohms
• d.60 ohms

Xc = 1/(2*pi*f*C) = 1/(2*pi*60*100x10^-6) = 1/0.0377 = 26.5 ohms. Capacitive reactance falls as frequency rises.

A series RLC circuit has L = 1 mH and C = 1 uF. What is its resonant frequency? (f = 1/(2*pi*sqrt(LC)))

• a.50.3 kHz
• b.5.03 kHz✓
• c.159 Hz
• d.1.59 kHz

sqrt(LC) = sqrt(10^-3 x 10^-6) = sqrt(10^-9) = 3.16x10^-5; f = 1/(2*pi*3.16x10^-5) = 5.03 kHz. At resonance the inductive and capacitive reactances cancel.

A sinusoidal voltage has a peak value of 170 V. What is its RMS value? (Vrms = Vpeak/sqrt(2))

• a.85 V
• b.170 V
• c.120 V✓
• d.240 V

Vrms = 170/sqrt(2) = 170/1.414 = 120 V. This is why standard 120 V mains has a peak near 170 V.

A series AC circuit has a resistance of 3 ohms and a reactance of 4 ohms. What is the magnitude of its impedance?

• a.7 ohms
• b.3.5 ohms
• c.5 ohms✓
• d.1 ohm

|Z| = sqrt(R^2 + X^2) = sqrt(3^2 + 4^2) = sqrt(25) = 5 ohms. Resistance and reactance combine as perpendicular components (a 3-4-5 triangle).

An ideal transformer has 1000 primary turns and 100 secondary turns. If 120 V is applied to the primary, what is the secondary voltage?

• a.120 V
• b.24 V
• c.1200 V
• d.12 V✓

Vs/Vp = Ns/Np, so Vs = 120 x (100/1000) = 12 V. A step-down turns ratio lowers voltage while raising available current.

An ideal step-down transformer delivers 12 V at 2 A to its load from a 120 V source. What primary current does it draw?

• a.0.2 A✓
• b.0.02 A
• c.20 A
• d.2 A

Ideal transformers conserve power: Vp*Ip = Vs*Is, so Ip = (12 x 2)/120 = 0.2 A. Stepping voltage down steps current up.

An AC load draws 5 A at 120 V with a power factor of 0.8. What is the real (average) power consumed?

• a.600 W
• b.480 W✓
• c.750 W
• d.384 W

Real power P = V*I*cos(theta) = 120 x 5 x 0.8 = 480 W. The power factor is the cosine of the phase angle between voltage and current.

In a single loop, a 12 V source drives current through two resistors. If one drops 5 V, what is the voltage across the other by Kirchhoff's voltage law?

• a.5 V
• b.12 V
• c.7 V✓
• d.17 V

KVL requires the drops to sum to the source: 12 - 5 = 7 V across the second resistor. The algebraic sum of voltages around any closed loop is zero.

At a circuit node, 3 A and 2 A flow in while one branch carries current out. By Kirchhoff's current law, what is the outgoing current?

• a.5 A✓
• b.6 A
• c.2.5 A
• d.1 A

KCL requires current in to equal current out: 3 + 2 = 5 A leaving the node. Charge is conserved, so none accumulates at a node.

A 10 A current enters two equal parallel resistors. How much current flows through each?

• a.5 A✓
• b.2.5 A
• c.10 A
• d.0 A

Equal parallel branches split the current equally: 10/2 = 5 A each. In a current divider, more current takes the lower-resistance path.

What current flows through a 12-ohm resistor connected across a 24 V source?

• a.12 A
• b.288 A
• c.0.5 A
• d.2 A✓

Ohm's law: I = V/R = 24/12 = 2 A. Current is proportional to voltage and inversely proportional to resistance.

Three identical 30-ohm resistors are connected in parallel. What is their equivalent resistance?

• a.10 ohms✓
• b.15 ohms
• c.30 ohms
• d.90 ohms

For n equal resistors in parallel, R_eq = R/n = 30/3 = 10 ohms. Adding parallel paths lowers the total resistance.

A resistor carries an AC current with RMS value 2 A through 10 ohms. What average power does it dissipate?

• a.40 W✓
• b.20 W
• c.10 W
• d.80 W

Average power in a resistor uses RMS values: P = Irms^2*R = 2^2 x 10 = 40 W. RMS is defined precisely so this DC-like power formula holds.

Under OSHA, the permissible noise exposure limit for an 8-hour workday is:

• a.120 dBA
• b.70 dBA
• c.140 dBA
• d.90 dBA✓

OSHA's 8-hour PEL for noise is 90 dBA, with a 5-dBA exchange rate that halves allowable time for each increase. A hearing-conservation program begins at the 85-dBA action level.

A vapor's concentration is below its lower explosive limit (LEL). The mixture is:

• a.In the ideal ignition range
• b.Too rich to ignite
• c.Too lean (too little fuel) to ignite✓
• d.Oxygen-enriched

Below the LEL there is too little fuel vapor for combustion (too lean); above the UEL it is too rich. Only between the LEL and UEL will the mixture ignite.

The fire tetrahedron adds which fourth element to the classic fire triangle of fuel, heat, and oxygen?

• a.Smoke
• b.A sustained chemical chain reaction✓
• c.Pressure
• d.Water

The tetrahedron adds the self-sustaining chemical chain reaction. Removing any one of the four elements (as dry-chemical agents do to the reaction) extinguishes the fire.

A Class B fire extinguisher is designed primarily for fires involving:

• a.Flammable liquids and gases✓
• b.Ordinary combustibles like wood and paper
• c.Energized electrical equipment
• d.Combustible metals

Class B covers flammable liquids and gases. Class A is ordinary combustibles, Class C is energized electrical equipment, and Class D is combustible metals.

The primary purpose of an OSHA lockout/tagout (LOTO) program is to:

• a.Provide fall protection at height
• b.Reduce airborne dust
• c.Control hazardous energy so machines cannot start during servicing✓
• d.Label chemical containers

LOTO isolates and de-energizes equipment and locks it out so stored or accidental energy cannot injure workers performing maintenance or servicing.

Under the OSHA Hazard Communication Standard (GHS-aligned), a Safety Data Sheet (SDS) has how many standardized sections?

• a.24
• b.8
• c.4
• d.16✓

The globally harmonized SDS format has 16 sections in a fixed order, from identification and hazards through handling, exposure controls, and disposal.

In radiation protection, the ALARA principle directs that exposures be kept:

• a.At the regulatory maximum
• b.Zero at all costs regardless of feasibility
• c.Exactly at background level
• d.As low as reasonably achievable✓

ALARA means As Low As Reasonably Achievable, balancing dose reduction against social and economic factors using time, distance, and shielding to minimize exposure.

The gray (Gy), the SI unit of absorbed radiation dose, is defined as:

• a.One roentgen per hour
• b.One radioactive disintegration event occurring each second
• c.One rem per year
• d.One joule of energy absorbed per kilogram of matter✓

1 Gy = 1 J/kg of absorbed energy. The sievert then weights the gray by radiation type to express biological dose equivalent.

In the hierarchy of hazard controls, which approach is considered most effective (highest priority)?

• a.Elimination of the hazard✓
• b.Administrative procedures
• c.Warning signs
• d.Personal protective equipment

Elimination (removing the hazard entirely) is most effective, followed by substitution, engineering controls, administrative controls, and finally PPE as the last line of defense.

Personal protective equipment (PPE) is placed where in the hierarchy of controls?

• a.It is not a control method
• b.First, as the preferred control
• c.Last, as the least effective control✓
• d.Equal to elimination

PPE is the least effective control because it protects only the wearer and only when used correctly; it is used when higher-level controls cannot fully remove the hazard.

OSHA generally requires fall protection in the construction industry at heights of:

• a.10 feet or more
• b.6 feet or more✓
• c.2 feet or more
• d.20 feet or more

In construction, fall protection is generally required at 6 feet above a lower level. General industry uses a 4-foot trigger height.

Before entering a permit-required confined space, the FIRST safety step is generally to:

• a.Remove all ventilation equipment
• b.Begin the assigned maintenance work as quickly as possible
• c.Assume the atmosphere is safe
• d.Test the atmosphere for oxygen, flammables, and toxics✓

Atmospheric testing for oxygen level, flammable gases, and toxic contaminants must precede entry, since invisible atmospheric hazards are the leading cause of confined-space fatalities.

Two identical machines each produce 80 dB of sound. Operating together as incoherent sources, their combined level is about:

• a.160 dB
• b.80 dB
• c.83 dB✓
• d.100 dB

Doubling sound power adds about 3 dB (10*log10(2) is about 3), so two equal 80-dB sources give roughly 83 dB, not 160 dB, because decibels are logarithmic.

In water-quality engineering, biochemical oxygen demand (BOD) measures:

• a.The dissolved salt content
• b.The overall acidity or alkalinity (pH) of the water sample
• c.The turbidity of the water
• d.The oxygen microbes consume to decompose organic matter✓

BOD quantifies the dissolved oxygen that microorganisms use to break down organic matter; a high BOD signals heavy organic pollution that can deplete a stream's oxygen.

Discharging a high-BOD effluent into a river primarily harms aquatic life by:

• a.Cooling the water
• b.Sharply raising the water's pH to chemically toxic levels
• c.Depleting dissolved oxygen as microbes consume it✓
• d.Increasing dissolved oxygen

Microbes decomposing the organic load consume dissolved oxygen faster than reaeration replaces it, causing an oxygen sag that can suffocate fish and other aquatic organisms.

A contaminant present at 2 mg/L in water corresponds to approximately how many ppm?

• a.2 ppm✓
• b.200 ppm
• c.20 ppm
• d.0.2 ppm

Because 1 L of water weighs about 1 kg (10^6 mg), 1 mg/L is about 1 ppm. Thus 2 mg/L is about 2 ppm. This equivalence holds for dilute aqueous solutions.

Carbon monoxide is especially dangerous in confined workspaces primarily because it:

• a.Is extremely flammable and readily forms explosive mixtures even at very low concentrations
• b.Is colorless, odorless, and binds hemoglobin far more strongly than oxygen✓
• c.Is strongly acidic
• d.Has a sharp warning odor

CO is colorless and odorless (no warning) and binds hemoglobin with roughly 200 times oxygen's affinity, forming carboxyhemoglobin and causing chemical asphyxiation.

The flash point of a liquid is the:

• a.Temperature at which the liquid spontaneously self-ignites in air with no external spark or flame
• b.Lowest temperature at which it gives off enough vapor to form an ignitable mixture✓
• c.Temperature at which it freezes
• d.Temperature at which it boils

Flash point is the minimum temperature at which a liquid produces sufficient vapor to flash when an ignition source is present. Autoignition, needing no spark, occurs at a higher temperature.

A chemical's Threshold Limit Value, Time-Weighted Average (TLV-TWA) represents the:

• a.Concentration that causes an explosion
• b.Instantaneous airborne concentration that would prove immediately lethal to an exposed worker on contact
• c.Average airborne concentration a worker may be exposed to over an 8-hour shift without adverse effect✓
• d.Odor detection threshold

TLV-TWA is the time-weighted average concentration for a normal 8-hour day and 40-hour week to which nearly all workers may be repeatedly exposed without adverse health effects.

In toxicology, the LD50 of a substance is the dose that:

• a.Just begins to cause mild irritation
• b.Causes a detectable odor
• c.Is lethal to 50% of a test population✓
• d.Is completely safe for all subjects

LD50 (median lethal dose) kills 50% of a test population; a lower LD50 means higher acute toxicity. It is a standard measure for comparing chemical hazards.

OSHA's recordable incident rate is normalized using a base of how many employee-hours, representing 100 full-time workers per year?

• a.200,000✓
• b.1,000,000
• c.100,000
• d.40,000

The rate = (recordable cases x 200,000)/total hours worked. The 200,000 base equals 100 workers x 40 hours x 50 weeks, allowing comparison across differently sized firms.

Which of the following is a form of ionizing radiation?

• a.Visible light
• b.Microwaves
• c.Gamma rays✓
• d.Radio waves

Gamma rays, along with X-rays and alpha and beta particles, carry enough energy to remove electrons from atoms (ionize) and damage tissue. Visible light, radio, and microwaves are non-ionizing.

Local exhaust ventilation is generally preferred over general dilution ventilation for a toxic contaminant because it:

• a.Increases the room contaminant concentration
• b.Requires no maintenance
• c.Captures the contaminant at its source before it spreads✓
• d.Uses no energy

Local exhaust captures contaminants at the point of generation, removing them before workers breathe them, which is more effective and lower-flow than diluting contaminated air throughout the room.

Redesigning a process so the hazard is removed entirely, rather than guarded against, reflects which principle?

• a.Engineering out the hazard (prevention through design)✓
• b.Posting more warning signs
• c.Accepting the residual risk
• d.Relying on PPE first

Prevention through design engineers the hazard out of the process itself, far more reliable than depending on worker behavior, signs, or PPE to manage a hazard left in place.

The NSPE Code of Ethics directs that engineers perform services only:

• a.When supervised by a lawyer
• b.For the highest-paying client
• c.In areas of their competence✓
• d.Within their home state

Engineers must undertake assignments only in their areas of competence. Working outside one's qualifications endangers the public and violates a fundamental canon.

Acting as a 'faithful agent or trustee' for each employer or client means an engineer must:

• a.Follow the employer's every instruction even when doing so would clearly endanger the public
• b.Always choose the cheapest design
• c.Conceal all project information from regulators
• d.Avoid conflicts of interest and act in the client's legitimate interests✓

The faithful-agent canon requires loyalty and honesty toward the client or employer, including disclosing conflicts, but never at the expense of the paramount duty to public safety.

An employer orders a design change the engineer believes will endanger the public. The engineer should:

• a.Delegate the decision to a junior engineer
• b.Refuse and notify the employer or an appropriate authority, because public safety is paramount✓
• c.Comply immediately with the order and assume the employer alone bears full responsibility for any resulting harm
• d.Quietly make the change and document nothing

The first canon, to hold public safety paramount, overrides employer instructions. The engineer must not proceed and should notify proper authorities if the danger is not corrected.

An engineer has a financial interest in a firm bidding on a project she is helping her client evaluate. She should:

• a.Promptly and fully disclose the conflict of interest to the client✓
• b.Say nothing about the interest so as not to jeopardize the ongoing client relationship or the fee
• c.Automatically award the contract to that firm
• d.Withdraw from all engineering practice

The Code requires engineers to disclose all known or potential conflicts of interest that could influence their judgment or the quality of their services, so the client can decide how to proceed.

Regarding a former client's proprietary information, an engineer must:

• a.Publish it to demonstrate expertise
• b.Keep it confidential and not use it against that client without consent✓
• c.Share it freely with the new client whenever doing so might speed the current project along
• d.Sell it to the highest bidder

Engineers must not disclose or use the confidential information of a present or former client for personal advantage or that of others without the client's prior consent.

Under the Code, an engineer may affix her professional seal (stamp) to:

• a.Plans she has never reviewed, for a fee
• b.Any drawing that a trusted colleague personally asks her to sign as a professional courtesy
• c.Only documents she prepared or that were prepared under her responsible charge✓
• d.Work in any discipline regardless of competence

Engineers may seal only work they personally prepared or directly supervised. 'Plan stamping' work one did not oversee is unethical and often illegal.

When issuing public statements on technical matters, engineers are required to be:

• a.Objective and truthful, and to disclose relevant interests✓
• b.Silent to avoid liability
• c.As persuasive as possible, whatever it takes to win public support for the project
• d.Aligned with whoever pays them

Engineers must issue public statements only in an objective and truthful manner, based on facts, and must reveal any interest they have in the matters discussed.

An engineer who uses a colleague's design work in a report should:

• a.Claim it as entirely his own
• b.Give credit to those to whom credit is due✓
• c.Charge the colleague a fee
• d.Delete all references to sources

The Code requires engineers to give credit for engineering work to those to whom credit is due and to recognize the proprietary interests of others; plagiarism is unethical.

Accepting a substantial gift from a supplier who hopes to influence the engineer's specification decision is:

• a.Encouraged to build relationships
• b.Required by professional courtesy
• c.A violation of the Code, which bars gifts intended to influence judgment✓
• d.Perfectly acceptable so long as the gift's value stays under some informal five-hundred-dollar limit

Engineers must not solicit or accept gratuities, directly or indirectly, from parties dealing with their client or employer in connection with work for which they are responsible.

An engineer discovers that a completed structure poses an imminent danger to occupants. The Code obligates her to:

• a.Notify her client or employer and, if not corrected, the proper authority✓
• b.Resign quietly without telling anyone
• c.Keep silent about the danger in order to protect the firm's reputation and avoid liability
• d.Wait until someone is injured

When public safety is endangered, engineers must notify their client or employer and, if the situation is not addressed, such other authority as may be appropriate. The duty to warn overrides confidentiality.

Sustainable development is commonly defined as development that:

• a.Maximizes short-term profit only
• b.Relies exclusively on renewable resources and permits no use of any nonrenewable material at all
• c.Meets present needs without compromising future generations' ability to meet theirs✓
• d.Ignores environmental limits

The Brundtland definition frames sustainability as meeting present needs without compromising the ability of future generations to meet their own, balancing economic, social, and environmental goals.

The Code's guidance that engineers 'continue their professional development' primarily means they should:

• a.Stop learning after licensure
• b.Change disciplines every year
• c.Train only subordinates, not themselves
• d.Keep their knowledge and skills current throughout their careers✓

Engineers should maintain and improve their technical competence through continuing education and should encourage the professional development of those under their supervision.

Misrepresenting one's qualifications or the material facts in a professional matter is:

• a.A minor courtesy issue
• b.Only a problem if discovered
• c.Generally acceptable behavior whenever one is competing hard for a valuable new engagement
• d.A violation of the Code's requirement to be honest and avoid deception✓

Engineers must be objective and truthful and must not engage in deceptive acts, including misrepresenting their qualifications, prior work, or facts material to a decision.