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Bac STI2D - independent subject practice study materials
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Bac STI2D - independent subject practice practice questions

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Question 1Engineering models, drawings, evidence and project decisions

In the STI2D systemic approach, every technical system is analysed through three interacting domains. Which set correctly names these three domains?

  1. Matter, energy and information Correct answer.
  2. Mass, force and speed
  3. Cost, quality and time
  4. Hardware, firmware and software

Explanation

The whole STI2D transversal programme is built on the 'matiere - energie - information' triad. Every studied object or installation is analysed in terms of the matter it processes, the energy it converts, and the information it handles.

Question 2Engineering models, drawings, evidence and project decisions

An automated system is classically decomposed into a 'chaine d'energie' and a 'chaine d'information'. What is the primary role of the chaine d'information?

  1. To store mechanical energy in flywheels
  2. To convert electrical energy into motion
  3. To acquire, process and transmit data to control the system Correct answer.
  4. To provide the structural frame of the product

Explanation

The chaine d'information acquires data (sensors), processes it (controller) and communicates it, in order to pilot the chaine d'energie. The chaine d'energie alimente, distribue, convertit and transmits energy to the effector.

Question 3Engineering models, drawings, evidence and project decisions

In SysML, which diagram is typically used to describe the use cases (cas d'utilisation) of a system, i.e. the services it renders to its actors?

  1. Use case diagram (uc) Correct answer.
  2. Sequence diagram (seq)
  3. Block definition diagram (bdd)
  4. State machine diagram (stm)

Explanation

The use case diagram (diagramme de cas d'utilisation, uc) shows the functions/services a system offers and the actors who interact with it. It answers 'what does the system do for whom?'.

Question 4Engineering models, drawings, evidence and project decisions

An ecart de performance is defined in STI2D as the difference between which two of the following?

  1. The cost and the selling price of a product
  2. The performance of two competing products
  3. The energy in and the energy out of a system
  4. Expected/measured performance and simulated/required performance Correct answer.

Explanation

STI2D analyses three 'ecarts': between expected and measured (cahier des charges vs reality), between measured and simulated (real vs model), and between expected and simulated (specification vs model). These gaps drive the engineering analysis of a system.

Question 5Engineering models, drawings, evidence and project decisions

A FAST diagram (Function Analysis System Technique) is read from left to right answering successive questions. The arrow from a function to a sub-function answers which question?

  1. Why is this function performed?
  2. When is this function performed?
  3. How is this function performed? Correct answer.
  4. Who performs this function?

Explanation

In a FAST diagram, moving rightward (towards technical solutions) answers 'How?' (comment), while moving leftward answers 'Why?' (pourquoi). This decomposes a service function into technical solutions.

Question 6Engineering models, drawings, evidence and project decisions

The 'bete a cornes' (horned-beast) diagram used in functional analysis answers three questions about a product. Which question does it NOT directly address?

  1. A qui le produit rend-il service? (Whom does it serve?)
  2. Sur quoi agit-il? (What does it act upon?)
  3. Dans quel but? (For what purpose?)
  4. Combien coute-t-il a fabriquer? (What is its production cost?) Correct answer.

Explanation

The bete a cornes captures the need: whom it serves, what it acts on, and in what aim. Production cost is an economic constraint addressed elsewhere (cahier des charges, eco-design), not by this need-expression tool.

Question 7Engineering models, drawings, evidence and project decisions

In the I2D exam, the first compulsory exercise asks candidates to analyse a pluritechnological product across the common themes. These themes are:

  1. Marketing, finance and law
  2. Matter, energy and information Correct answer.
  3. Biology, geology and chemistry
  4. History, geography and civics

Explanation

The common (transversal) exercise of the 2I2D written paper assesses knowledge in matter, energy and information on a real pluritechnological system, before the specialty-specific exercise.

Question 8Engineering models, drawings, evidence and project decisions

A 'systeme asservi' (closed-loop / servo system) is characterised by the presence of which element compared with an open-loop system?

  1. A power supply
  2. A mechanical reducer
  3. A feedback (return / capteur de mesure) comparing output to the setpoint Correct answer.
  4. A user interface

Explanation

A closed-loop (asservi) system measures its output with a sensor and compares it to the setpoint (consigne); the error drives a correction. The feedback loop is what distinguishes it from an open-loop command.

Question 9Engineering models, drawings, evidence and project decisions

In SysML, a requirement diagram (diagramme d'exigences, req) is principally used to:

  1. Show the physical assembly of parts
  2. Capture and trace the requirements of the cahier des charges Correct answer.
  3. Describe the sequence of messages over time
  4. List the materials used in the product

Explanation

The requirement diagram formalises the cahier des charges as structured, traceable requirements and links them to the elements that satisfy or verify them. It supports verification and validation of the design.

Question 10Engineering models, drawings, evidence and project decisions

A 'modele de comportement' (behaviour model) is used in STI2D mainly to:

  1. Replace the real system permanently in production
  2. Predict and simulate the system's performance before realisation Correct answer.
  3. Define the selling price
  4. Translate the product manual into other languages

Explanation

Behaviour models (numerical simulations) let students predict performances and compare them with expected and measured values, identifying ecarts. In STI2D students mainly USE proposed models rather than build them.

Question 11Engineering models, drawings, evidence and project decisions

Innovation in STI2D is distinguished from invention because an innovation must additionally:

  1. Be patented worldwide
  2. Use only new materials
  3. Find a market / be adopted and create value in use Correct answer.
  4. Be designed by a single engineer

Explanation

An invention becomes an innovation only when it reaches the market and is adopted, creating value. STI2D stresses that innovation links technical novelty to economic and social usefulness.

Question 12Engineering models, drawings, evidence and project decisions

A 'rupture' (disruptive) innovation differs from an 'incremental' innovation because a disruptive innovation:

  1. Slightly improves an existing product
  2. Introduces a fundamentally new concept or technology that may displace existing markets Correct answer.
  3. Only reduces production cost
  4. Changes only the colour of a product

Explanation

Disruptive (de rupture) innovation introduces a radically new technology or use that can replace existing solutions, whereas incremental innovation makes successive small improvements to an existing product.

Question 13Engineering models, drawings, evidence and project decisions

The 'competitivite' (competitiveness) of a product depends on balancing several factors. Which trio best captures the classic competitiveness triangle?

  1. Cost, quality and delay (delai) Correct answer.
  2. Weight, colour and brand
  3. Voltage, current and power
  4. Length, width and height

Explanation

Industrial competitiveness is classically the trade-off between cost, quality and lead time (delai). A competitive product optimises all three to satisfy the customer better than rivals.

Question 14Engineering models, drawings, evidence and project decisions

In value analysis (analyse de la valeur), the 'value' of a function is best expressed as:

  1. The ratio of the function's satisfaction to its cost Correct answer.
  2. The mass of the part performing it
  3. The number of components used
  4. The price charged to the customer

Explanation

Value analysis defines value as the ratio of the satisfaction (importance/performance) a function provides to the cost of achieving it. Designers seek to raise satisfaction and/or lower cost to maximise value.

Question 15Engineering models, drawings, evidence and project decisions

A CAD (CAO) model is used in STI2D design. The main advantage of a parametric CAD model is that:

  1. It cannot be modified once created
  2. Changing a parameter automatically updates the linked geometry Correct answer.
  3. It only stores 2D drawings
  4. It removes the need for any simulation

Explanation

In parametric CAD, dimensions are driven by parameters; modifying one parameter updates the whole linked geometry automatically. This speeds up design iteration and what-if studies.

Question 16Engineering models, drawings, evidence and project decisions

The 'demarche de projet' (project approach) in STI2D follows a logical sequence. Which step normally comes FIRST?

  1. Industrialisation and mass production
  2. Analysis of the need and specification (cahier des charges) Correct answer.
  3. Recycling at end of life
  4. Marketing campaign

Explanation

A project starts by analysing the need and drafting the cahier des charges (specifications). Design, prototyping, testing and production follow only once the requirements are clear.

Question 17Engineering models, drawings, evidence and project decisions

Industrial property protection in France for a technical invention is obtained through which body, studied in the innovation chapter?

  1. INSEE
  2. INPI (Institut National de la Propriete Industrielle) Correct answer.
  3. AFNOR
  4. ADEME

Explanation

The INPI delivers patents (brevets) protecting technical inventions in France. STI2D covers industrial property as part of protecting and valorising innovation.

Question 18Engineering models, drawings, evidence and project decisions

The STI2D series prepares students mainly for which kind of higher education and goals?

  1. Purely professional employment with no further study
  2. Scientific and technological higher studies (BTS, BUT, engineering schools, CPGE TSI) Correct answer.
  3. Medical school exclusively
  4. Fine-arts conservatoires

Explanation

STI2D was recentred on technological objectives (not professional/job-ready) to prepare students for higher studies: BTS, BUT, engineering schools, universities and CPGE of the TSI pathway. It emphasises scientific competences for the supérieur.

Question 19Engineering models, drawings, evidence and project decisions

The four specialty fields (enseignements specifiques) chosen in Terminale STI2D are AC, EE, ITEC and SIN. Which describes ITEC correctly?

  1. Architecture and construction of buildings
  2. Production and management of energy
  3. Innovation technologique et eco-conception of industrial products Correct answer.
  4. Networks, programming and embedded systems

Explanation

ITEC (Innovation technologique et eco-conception) focuses on designing industrial products with mechanics, automation and eco-design. AC is construction, EE is energy, SIN is information and digital systems.

Question 20Engineering models, drawings, evidence and project decisions

When analysing a real pluritechnological system, STI2D identifies an 'ecart' between the simulated model and the measured behaviour. The recommended engineering response is to:

  1. Ignore the ecart since models are always right
  2. Investigate hypotheses, refine the model or the measurement to reduce the ecart Correct answer.
  3. Discard the real system
  4. Stop the project immediately

Explanation

An ecart between model and measurement signals that the model's hypotheses or the measurement need revisiting. The engineering approach analyses the causes and refines the model or test to converge, validating the design.

Question 21Materials, testing and selection

A material with a high recyclability rate but produced from a scarce, energy-intensive ore presents a trade-off. Eco-design resolves such trade-offs by:

  1. Always choosing the cheapest material
  2. Comparing impacts across the whole life cycle using multi-criteria indicators Correct answer.
  3. Ignoring the production phase
  4. Selecting only metals

Explanation

Eco-design uses multi-criteria life-cycle analysis to weigh competing impacts (extraction energy, recyclability, use, disposal). No single criterion decides; the goal is the lowest overall environmental impact.

Question 22Materials, testing and selection

A structure subjected to a pulling force along its axis is said to be in:

  1. Compression
  2. Traction (tension) Correct answer.
  3. Torsion
  4. Shear (cisaillement)

Explanation

An axial pulling load that tends to lengthen a member puts it in traction (tension). The internal normal stress is tensile and equals the force divided by the cross-sectional area.

Question 23Materials, testing and selection

The normal stress (contrainte normale) sigma in a bar of cross-section S under an axial force N is given by which relation?

  1. sigma = N x S
  2. sigma = N / S Correct answer.
  3. sigma = S / N
  4. sigma = N + S

Explanation

Normal stress equals the axial force divided by the cross-sectional area: sigma = N / S, expressed in pascals (Pa) when N is in newtons and S in square metres. Engineers compare it to the material's allowable stress.

Question 24Materials, testing and selection

The principe fondamental de la statique (PFS) for a body in equilibrium states that:

  1. The sum of the masses equals zero
  2. The sum of external forces and the sum of external moments are both zero Correct answer.
  3. The kinetic energy is maximal
  4. The velocity is constant and non-zero

Explanation

For static equilibrium, the resultant of external forces is zero and the resultant moment about any point is zero. STI2D uses this, often via the triangle des forces for three coplanar forces, to find reactions.

Question 25Materials, testing and selection

When three coplanar, non-parallel forces hold a solid in equilibrium, their lines of action must:

  1. Be parallel to each other
  2. Be concurrent (pass through a single point) Correct answer.
  3. Form a right angle
  4. Be equal in magnitude

Explanation

For a solid in equilibrium under three coplanar forces, the lines of action are concurrent (intersect at one point) and the forces close a triangle des forces. This property lets students solve graphically for unknown reactions.

Question 26Materials, testing and selection

A composite material studied in STI2D, such as glass-fibre reinforced polymer, combines a matrix and a reinforcement to obtain:

  1. Lower strength than each component
  2. A favourable strength-to-weight ratio not achievable by either component alone Correct answer.
  3. Pure electrical superconductivity
  4. Identical properties to a single metal

Explanation

A composite combines a matrix (polymer) and a reinforcement (fibres) so the assembly has a higher strength-to-weight ratio than either alone. This is why composites are used to lighten structures in eco-design.

Question 27Materials, testing and selection

The yield strength (limite elastique, Re) of a structural material is defined as:

  1. The stress beyond which permanent (plastic) deformation begins Correct answer.
  2. The stress at which the material melts
  3. The maximum strain before any deformation
  4. The density of the material

Explanation

The yield strength Re is the stress above which deformation is no longer reversible (plastic, permanent). Designers keep working stress below Re, applying a safety factor, to ensure the structure returns to shape after loading.

Question 28Materials, testing and selection

A safety factor (coefficient de securite) of 3 applied to a material whose yield strength is 240 MPa gives an allowable working stress of:

  1. 720 MPa
  2. 243 MPa
  3. 80 MPa Correct answer.
  4. 237 MPa

Explanation

The allowable stress equals the yield strength divided by the safety factor: 240 / 3 = 80 MPa. Working below this value guards against uncertainties in loads, materials and manufacturing.

Question 29Materials, testing and selection

In a reinforced-concrete beam (poutre en beton arme) studied in the AC specialty, the steel reinforcement bars are placed mainly to:

  1. Resist compression at the top
  2. Increase the beam's colour
  3. Resist tension where the concrete would crack Correct answer.
  4. Reduce the beam's electrical resistance

Explanation

Concrete resists compression well but is weak in tension. Steel bars are placed in the tensile zone (typically the underside of a simply-supported beam) to carry the tensile stresses the concrete cannot.

Question 30Materials, testing and selection

The thermal resistance R of a building wall (in the AC specialty) is linked to the U-value (coefficient de transmission thermique) by:

  1. U = R
  2. U = 1 / R Correct answer.
  3. U = R squared
  4. U = R + 1

Explanation

The thermal transmittance U is the reciprocal of the thermal resistance: U = 1/R (W per m2 per K). A high R (good insulation) gives a low U and lower heat loss, a core idea in energy-efficient construction.

Question 31Building systems, load paths, heat and moisture

In the AC (architecture et construction) specialty, a bioclimatic design (conception bioclimatique) of a building aims to:

  1. Maximise reliance on fossil heating
  2. Use the site, orientation and natural light/heat to reduce energy needs Correct answer.
  3. Ignore the local climate
  4. Increase the building's grey energy

Explanation

Bioclimatic design uses orientation, solar gains, natural ventilation and insulation to minimise heating, cooling and lighting demand. It is a core eco-construction strategy in the AC specialty.

Question 32Building systems, load paths, heat and moisture

According to reinforced concrete design rules (BAEL 91 / Eurocode 2), what is the primary fundamental reason steel rebars are embedded in the tension zone of a concrete beam?

  1. Concrete has high compressive strength but very low tensile strength (typically ~10% of compressive strength) Correct answer.
  2. Steel prevents the concrete from absorbing environmental humidity
  3. Steel increases the chemical hydration rate of Portland cement
  4. Concrete cannot withstand shear stresses under any loading condition

Explanation

Concrete is strong in compression (fc28 ≈ 20–40 MPa) but weak and brittle in tension (ft28 ≈ 2–3 MPa). In a flexural beam, steel reinforcement is placed in regions experiencing tensile stress to carry the tension forces once the concrete cracks.

Question 33Building systems, load paths, heat and moisture

In limit state design of reinforced concrete (BAEL 91 / Eurocode), what is the standard load combination for the Ultimate Limit State (ULS / ELU) for fundamental persistent situations with dead load G and live load Q?

  1. 1.35 G + 1.5 Q Correct answer.
  2. G + Q
  3. 1.0 G + 1.35 Q
  4. 1.5 G + 1.35 Q

Explanation

Under BAEL 91 and Eurocode fundamental load combinations for Ultimate Limit State (ELU), the design load is given by 1.35 · G + 1.5 · Q (where 1.35 is the partial safety factor for permanent loads γG and 1.5 is for variable live loads γQ).

Question 34Building systems, load paths, heat and moisture

A simply supported reinforced concrete beam with span L = 6.0 m carries a total uniform ultimate load of qu = 40 kN/m. What is the maximum ultimate bending moment Mu at mid-span?

  1. Mu = 180 kN·m Correct answer.
  2. Mu = 240 kN·m
  3. Mu = 120 kN·m
  4. Mu = 360 kN·m

Explanation

For a simply supported beam with uniformly distributed load qu over span L, the maximum bending moment at mid-span is Mu = (qu · L^2) / 8 = (40 · 6.0^2) / 8 = (40 · 36) / 8 = 1440 / 8 = 180 kN·m.

Question 35Building systems, load paths, heat and moisture

A square isolated footing has dimensions B × B = 2.0 m × 2.0 m and supports a vertical column service load of Nser = 800 kN. What is the applied ground contact pressure σ applied to the soil?

  1. σ = 200 kPa (0.20 MPa) Correct answer.
  2. σ = 400 kPa (0.40 MPa)
  3. σ = 100 kPa (0.10 MPa)
  4. σ = 800 kPa (0.80 MPa)

Explanation

The base area of the footing is A = B · B = 2.0 m · 2.0 m = 4.0 m^2. The uniform soil bearing stress is σ = Nser / A = 800 kN / 4.0 m^2 = 200 kPa (or 0.20 MPa).

Question 36Building systems, load paths, heat and moisture

What is the primary role of the slump test (essai d'affaissement au cône d'Abrams) performed on fresh concrete on a construction site?

  1. To assess the workability and consistency (plasticity/fluidity) of the fresh concrete mix Correct answer.
  2. To measure the 28-day characteristic compressive strength fc28 directly
  3. To determine the chemical setting time of tricalcium aluminate
  4. To verify the tensile bond strength between steel rebar and cement matrix

Explanation

The slump test using Abrams cone measures the settlement (affaissement in mm) of fresh concrete under its own weight after removal of the mold. It quantifies mix consistency and workability (fluidity), indicating whether the water-cement ratio and admixtures are correct for placement.

Question 37Building systems, load paths, heat and moisture

In civil engineering soil mechanics, the plasticity index (Indice de Plasticité IP) of a soil is calculated from the Liquid Limit (wL) and Plastic Limit (wP) as IP = wL - wP. If a clay sample has wL = 58% and wP = 26%, how is this soil classified according to standard soil plasticity classification?

  1. High plasticity soil (IP = 32% > 17%) Correct answer.
  2. Low plasticity silty soil (IP = 8%)
  3. Non-plastic sandy gravel (IP = 0%)
  4. Liquid slurry with zero shear strength (IP = 84%)

Explanation

IP = wL - wP = 58% - 26% = 32%. In geotechnical classification (Atterberg limits), soils with IP > 17% (and especially IP > 25-30%) are classified as highly plastic clays (sols très plastiques / argiles très plastiques).

Question 38Energy, thermal machines and environmental assessment

In a flow representation (representation des flux), a flow of information differs from a flow of energy mainly because information flows:

  1. Always carry significant power
  2. Carry data with negligible power compared with energy flows Correct answer.
  3. Cannot be digital
  4. Only exist inside the chaine d'energie

Explanation

Information flows transport data (measurements, commands) and convey negligible power compared with energy flows. This is why a low-power sensor signal can pilot a high-power actuator through the chaine d'energie.

Question 39Energy, thermal machines and environmental assessment

Eco-conception (eco-design) is defined as the integration of environmental considerations into product design. At which stage are these considerations introduced?

  1. Only at end of life (recycling)
  2. Only during manufacturing
  3. From the very beginning of the design process Correct answer.
  4. Only after the product is sold

Explanation

Eco-design integrates environmental criteria from the earliest design stages, considering the entire life cycle. Acting early gives the greatest leverage to reduce environmental impact at lowest cost.

Question 40Energy, thermal machines and environmental assessment

An Analyse du Cycle de Vie (ACV / Life Cycle Assessment) studies a product's environmental impact across all life phases. Which sequence correctly orders the main phases?

  1. Use, extraction, manufacturing, end of life
  2. Extraction of raw materials, manufacturing, distribution, use, end of life Correct answer.
  3. Manufacturing, extraction, end of life, use
  4. End of life, use, distribution, extraction

Explanation

A life-cycle assessment follows the product 'from cradle to grave': raw-material extraction, manufacturing, distribution/transport, use, then end of life (recycling/disposal). Impacts are quantified at each stage.

Question 41Energy, thermal machines and environmental assessment

Sustainable development (developpement durable) is classically represented by three interdependent pillars. Which set lists them correctly?

  1. Economic, social and environmental Correct answer.
  2. Political, military and cultural
  3. Industrial, agricultural and digital
  4. Local, national and global

Explanation

Sustainable development balances three pillars: economic viability, social equity and environmental protection. A durable solution must satisfy all three simultaneously, the central principle behind STI2D's environmental focus.

Question 42Energy, thermal machines and environmental assessment

In a life-cycle assessment, the 'carbon footprint' indicator is usually expressed in which unit?

  1. kWh
  2. kg CO2 equivalent Correct answer.
  3. Joules per kelvin
  4. Decibels

Explanation

The carbon footprint aggregates greenhouse-gas emissions into a single indicator expressed in kilograms of CO2 equivalent (kg CO2 eq), weighting each gas by its global-warming potential.

Question 43Energy, thermal machines and environmental assessment

The 'energie grise' (embodied / grey energy) of a product corresponds to:

  1. The energy it consumes during use
  2. The energy lost as heat by friction
  3. Only the electrical energy of its battery
  4. The total energy needed to produce, transport and dispose of it, excluding use Correct answer.

Explanation

Embodied (grey) energy is the cumulative energy required to extract raw materials, manufacture, transport and dispose of a product, excluding its energy of use. It is a key eco-design indicator for material choice.

Question 44Energy, thermal machines and environmental assessment

Among recycling strategies, 'reutilisation' (reuse) is generally preferred over recycling because reuse:

  1. Requires more energy
  2. Keeps the product or part in service without reprocessing the material Correct answer.
  3. Always destroys the product
  4. Produces more waste

Explanation

Reuse keeps a product or component in service as-is (or after minor repair), avoiding the energy and material losses of recycling, which reprocesses the material into a new product. The waste hierarchy favours reduce, reuse, then recycle.

Question 45Energy, thermal machines and environmental assessment

Which French/European energy label is commonly studied in STI2D to communicate the energy efficiency class of household appliances, ranked from A to G?

  1. The NF logo
  2. The European energy label (etiquette energie) Correct answer.
  3. The CE marking
  4. The Triman logo

Explanation

The European energy label (etiquette energie) ranks appliances by energy-efficiency class, now from A (most efficient) to G after the 2021 rescaling. It informs consumers and drives eco-design of appliances.

Question 46Energy, thermal machines and environmental assessment

The efficiency (rendement) of an energy converter is defined as the ratio of:

  1. Input power to output power
  2. Mass to volume
  3. Useful output energy (or power) to input energy (or power) Correct answer.
  4. Voltage to current

Explanation

Efficiency eta = useful output / input, always between 0 and 1 (or as a percentage). The difference corresponds to losses, mostly dissipated as heat. The principle of energy conservation guarantees output never exceeds input.

Question 47Energy, thermal machines and environmental assessment

For a single-phase AC load in sinusoidal steady state, the active power is P = U x I x cos(phi). The factor cos(phi) is called the:

  1. Apparent power
  2. Reactive power
  3. Frequency
  4. Power factor (facteur de puissance) Correct answer.

Explanation

cos(phi) is the power factor, the cosine of the phase shift between voltage and current. A low power factor means more current is drawn for the same active power, increasing losses, which is why correction is studied in EE.

Question 48Energy, thermal machines and environmental assessment

Energy E and power P are linked by E = P x t. A 1500 W heater running for 2 hours consumes how much energy in kilowatt-hours?

  1. 3 kWh Correct answer.
  2. 0.75 kWh
  3. 750 kWh
  4. 3000 kWh

Explanation

E = P x t = 1500 W x 2 h = 3000 Wh = 3 kWh. The kilowatt-hour is the practical energy unit used on electricity bills and in EE energy audits.

Question 49Energy, thermal machines and environmental assessment

In an energy storage comparison, a lithium-ion battery is preferred over a lead-acid battery for portable applications mainly because the Li-ion battery has a higher:

  1. Mass (heavier)
  2. Self-discharge rate
  3. Energy density (Wh per kg) Correct answer.
  4. Internal resistance

Explanation

Lithium-ion cells store more energy per unit mass and volume (higher energy density, ~150-250 Wh/kg) than lead-acid, making them lighter for the same capacity, which is why they dominate portable and EV applications.

Question 50Energy, thermal machines and environmental assessment

The speed of an electromagnetic wave (such as light) in vacuum is approximately:

  1. 3 x 10^8 m/s Correct answer.
  2. 340 m/s
  3. 3 x 10^5 m/s
  4. 1.5 x 10^3 m/s

Explanation

Electromagnetic waves travel at c = 3.00 x 10^8 m/s in vacuum. This constant links wavelength and frequency (c = lambda x f) in the 'Ondes et signaux' chapter.