Science and Technology & Applied Science and Technology Exam Support Document Notes

The Earth and Space

Biogeochemical Cycles

  • Carbon Cycle (ST & AST):
    • Students may be tested on this concept in conjunction with permafrost, greenhouse effect, energy resources, combustion, photosynthesis, and respiration.

Lithosphere

  • Permafrost (ST & AST):
    • Increasing amounts of CO_2 and methane, soil instability (landslides), increasing amounts of vegetation, and changing ecosystems are direct consequences of melting permafrost.
    • Students could be tested on this concept in conjunction with the greenhouse effect and carbon cycle.

Hydrosphere

  • Watershed/Catchment Area (ST & AST):

    • A watershed or catchment area is a territory marked off by natural boundaries surrounding a network of rivers and streams, including groundwater and surface runoff.
    • These natural boundaries are known as watershed divides.
    • "Upstream" refers to any location above a given position along a watercourse.
    • "Downstream" refers to any location below that position along the watercourse.
    • Subwatersheds feed a watershed and function in the same way as a watershed.
    • Human activities impacting watersheds: creating a reservoir or navigation channel, irrigating soil, and draining or filling wetlands.
    • "Watershed divide" is the English equivalent for the French term "ligne de crête."

  • Ocean Circulation, Glacier and Pack Ice, Salinity (ST & AST):

    • These concepts are interrelated.
    • Pack ice consists of brackish water (mixture of fresh and salt water).
    • Salinity of pack ice is lower than the salt water in which it forms.
    • When pack ice forms, salt is discharged into the water, increasing its salinity and density, affecting thermohaline circulation.
    • Pack ice refers to large slabs of floating ice crowded together.
    • An ice floe is a free-floating sheet of ice.
    • Indirect consequences of melting glaciers and pack ice: disruption of ocean and thermohaline circulation, species displacement/extinction, new waterways, decrease in Earth's albedo.
    • Direct result of melting glaciers: rising sea levels.
    • Earth’s rotation influences surface currents only.

Atmosphere

  • Greenhouse Effect (ST & AST):

    • Students could be tested on this concept in conjunction with the carbon cycle, permafrost, combustion, photosynthesis, respiration, and energy resources.
    • Diagrams may be used in exam questions pertaining to this concept.

  • Cyclone and Anticyclone (ST & AST):

    • "Cyclone" and "anticyclone" are the terms used in ministerial examinations.
    • Only atmospheric convection will be covered in ministerial examinations to explain their formation.
    • Air temperature and humidity are characteristics to consider; humidity determines cloud cover.
    • Normal atmospheric pressure: 101.3 kPa (reference point for high/low-pressure systems).
    • Avoid using "good weather" and "bad weather" as they are subjective.

Space

  • Earth-Moon System (Gravitational Effect) (ST & AST):
    • Students can be tested on this concept; no additional clarifications provided.

Lithosphere/Hydrosphere/Atmosphere/Space

  • Energy Resources (ST & AST):
    • Geothermal, wind, marine-current, river-related, tidal, solar, and nuclear energy do not generate greenhouse gases when used.
    • Greenhouse gases generated during building, transporting, and dismantling facilities are considered minimal.
    • The renewable or non-renewable nature of a resource may be tested in conjunction with other characteristics.
    • Ministerial examinations may include questions on the advantages, disadvantages, and impacts of using different energy resources.
    • ST: energy resources could be tested with carbon cycle, combustion, and greenhouse effect.
    • AST: energy resources could be tested with combustion.

The Material World

Physical Properties of Solutions

  • Concentration (g/L, %, ppm) (ST & AST):

    • Solutions mentioned in the examinations are mostly aqueous, but solid homogeneous mixtures (concentration in m/m) may also be considered.

  • pH Scale (ST & AST):

    • A color chart of acid-base indicators may be provided for pH determination.
    • Interpreting mixtures of indicators will not be required.
    • Students may need to determine if a solution is acidic, basic, or neutral based on the molecular formula.
    • Strong vs. weak acids/bases are distinguished by their position on the pH scale.
    • A strong acid cannot be a weak base, and vice versa.
    • Example: a solution with a pH of 12 is a strong base and not a weak acid.
    • The logarithmic nature of the pH scale can be used to compare pH values.
    • Example: a solution with a pH of 12.5 is 100 times more basic than one with a pH of 10.5.
    • If pH > 7, terms "alkaline solution" or "basic solution" may be used.
    • Students are expected to know whether everyday substances are acidic, basic, or neutral.
    • Concepts that may be tested together: acid-base neutralization reaction and electrical conductivity.

  • Ions (ST & AST):

    • The exact charge of a monatomic ion may be determined by its position in the periodic table.
    • Concepts that may be tested together: groups and periods in the periodic table and electrical conductivity.

  • Electrical Conductivity (ST & AST):

    • A solution conducts electricity only if mobile ions are formed when an electrolyte (or solute) dissolves in water.
    • Students may need to identify conducting solutions based on the molecular formula of the compound involved.
    • The electrical conductivity of an everyday substance can be determined by its nature.
    • Concepts that may be tested together: pH scale and ions.

Chemical Changes

  • Combustion (ST & AST):

    • Terms used with the fire triangle: "oxidizing agent," "fuel," and "ignition temperature."
    • Ignition temperature is a characteristic property of a substance and is always the same.
    • Possible concept combinations: Energy resources; In ST: Carbon cycle and Greenhouse effect.

  • Oxidation (ST & AST):

    • Oxidation is a type of combustion.

  • Photosynthesis and Respiration (ST & AST):

    • Students could be tested on these concepts in conjunction with the carbon cycle and greenhouse effect.

  • Acid-Base Neutralization Reaction (ST & AST):

    • A color chart of different indicators may be provided to determine the pH of solutions in the reaction.
    • Students may need to recognize the molecular formula of an acid, a base, or a salt consisting of one polyatomic ion (radical) (e.g., H2SO4, Mg(OH)2, CaCO3).
    • Consider the neutralizing capacity of strong vs. weak acids/bases.
    • Students may need to identify the neutralizing substance based on the molecular formula.
    • Concepts for combined testing: pH scale and balancing chemical equations.

  • Balancing Chemical Equations (ST & AST):

    • Balanced equations must be in their simplest form (smallest possible natural number coefficients).
    • Part B: Balancing equations with polyatomic ions not required, but Part A requires determining if such equations are correctly balanced.
    • Concepts for combined testing: Acid-base neutralization reaction.

  • Law of Conservation of Mass (ST & AST):

    • Environmental Science and Technology option students should ideally not use stoichiometry to verify the law because their answer might slightly differ from the expected answer.

Organization of Matter

  • Rutherford-Bohr Atomic Model (ST & AST):

    • Students must associate the atomic number of an element with the number of protons.
    • Including neutrons is not considered a mistake.
    • Part B: Drawing diagrams beyond calcium (atomic number 20) not required, but Part A requires recognizing atoms with atomic numbers > 20 belonging to groups IA, IIA, VIIA, and VIIIA.
    • Possible concept combinations: groups and periods in the periodic table.

  • Groups and Periods in the Periodic Table (ST & AST):

    • Four groups with specific names: alkali metals, alkaline earth metals, halogens, and noble gases.
    • Other groups identified by the first element in their column (e.g., carbon group).
    • Group numbers indicated in Arabic numerals (1 to 18) or Roman numerals followed by A (IA to VIIIA).
    • "Noble gases" will be used to refer to Group VIIIA (or Group 18).
    • Study of the periodic table is not limited to the first 20 or 36 elements.
    • Students are not required to know the name associated with each element symbol.
    • Possible concept combinations: ions and the Rutherford-Bohr atomic model.

Electricity

  • Electrical Charge (ST & AST):

    • Students must be able to deduce the behavior (attraction or repulsion) of two charged objects based on their electrical charges (opposite or same signs).
    • Concepts that may be tested together: static electricity.

  • Static Electricity (ST & AST):

    • The transfer of electrons from one object to another can be deduced based on a triboelectric series (electrostatic list) or a series of actions (conduction, friction).
    • Phrases used: "gives up negative charges" and "acquires negative charges."
    • Induction is the displacement of negative charges within a neutral object near a charged object.
    • Concepts that may be tested together: electrical charge.

  • Ohm’s Law (ST & AST):

    • Mathematical relationship or graph can determine resistance, potential difference, and electric current intensity.
    • Electric current intensity can be expressed in milliamperes (mA).
    • Only "potential difference" is used instead of "voltage."
    • Possible concept combinations: electrical functions, electrical circuits, energy efficiency, or the relationship between power and electrical energy.

  • Electrical Circuits (ST & AST):

    • The position of components transforming energy determines the type of circuit (series or parallel).
    • Switches are not energy transformers; their position determines the operating state (open or closed), not the circuit type.
    • When the switch is open, current cannot flow.
    • Students must recognize symbols in a given circuit diagram.
    • If asked to draw a diagram, a list of symbols will be provided.
    • Possible concept combinations: electrical functions and Ohm's law.

  • Relationship Between Power and Electrical Energy (ST & AST):

    • Mathematical relationship or graph to determine power, time, and electrical energy.
    • Units of energy commonly used: joule (J), watt-hour (W·h or Wh), and kilowatt-hour (kW·h or kWh).
    • Electric current intensity can also be expressed in milliamperes (mA).
    • Determine whether an electrical appliance is more economical based on energy consumption without calculating the cost.
    • Possible concept combinations: energy efficiency and Ohm's law.

Electromagnetism

  • Forces of Attraction and Repulsion (ST & AST):

    • Students must be able to compare the behavior of a compass in the magnetic field of different magnets (bar, horseshoe, and circular).

  • Magnetic Field of a Live Wire & Magnetic Field of a Solenoid (ST & AST):

    • The direction of the current should be determined according to the polarity of the terminals (+ and -) indicated on the source or the ends of the wires.
    • Describing the magnetic field by drawing a diagram of field lines may be requested.

  • Electromagnetic Induction (ST & AST):

    • Students could be tested on this concept in conjunction with energy resources, since different types of power plants use electromagnetic induction to produce electrical energy.

Transformation of Energy

  • Law of Conservation of Energy (ST & AST):

    • "Energy dissipated" refers to energy not converted into a useful form in an open system (not isolated).
    • Other expressions, such as "energy lost," are not used.
    • Concept combination: transformation of energy as an electrical function.

  • Energy Efficiency (ST & AST):

    • Calculated as the ratio between useful energy and energy consumed, expressed as a percentage (%).
    • Concept combination: relationship between power and electrical energy and Ohm's law.

Fluids

  • Archimedes’ Principle (ST & AST):

    • Possible concept combinations: mass and weight and types of forces.

  • Pascal’s Principle (ST & AST):

    • Pressure (P = F/A) may be applied to help understand Pascal's principle qualitatively and quantitatively using simple proportions.

  • Bernoulli’s Principle (ST & AST):

    • Applies to different fluids (air, water, and other liquids) similar to Pascal’s and Archimedes’ principles.
    • Examination questions will focus only on the change in speed and its effect on pressure.

Force and Motion

  • Types of Forces (ST & AST):

    • Examination questions can focus on magnetic, gravitational, frictional, and driving forces.
    • Possible concept combinations: mass and weight and Archimedes’ principle.

  • Equilibrium of Two Forces (ST & AST):

    • Examination questions involve objects whose equilibrium might be disrupted when subjected to forces.
    • Students could be asked to determine the force that will maintain the equilibrium of a given object.

  • Relationship Between Constant Speed, Distance, and Time (ST & AST):

    • The formula v = d/\Delta t applies to the calculation of both average and constant speed.

  • Force (ST):

    • In ministerial examinations, a force is represented by a hollowed-out vector and the symbol for motion is an ordinary arrow.

  • Mass and Weight (ST & AST):

    • Students can be tested on this concept in conjunction with: types of forces and Archimedes’ principle.

The Technological World

Graphical Language

  • Multiview Orthogonal Projection (General Arrangement Drawings) (ST & AST):

    • Students may need to interpret general arrangement drawings of a technical object with few components and draw the top, front, and right-side views of the object.

  • Functional Dimensioning (ST & AST):

    • Dimensioning and tolerance applied from Secondary III to Secondary IV.

    • Dimensioning:

      • The set of dimensions that must be observed to manufacture and assemble an object, ensuring it works properly.
      • May include a tolerance.

    • Tolerance:

      • Precision (permitted deviation) required for all components.
      • Often indicated by a ± sign.
      • Expressed in four different ways (e.g., for a measurement of 32.5 mm):
        • 32.5^{+0.1}_{-0.2}
        • 32.502
        • 32.5
        • 32.5 \pm 1
      • Components may have slightly different measurements during manufacturing, hence tolerances.
      • Example:
        • Dimension with a tolerance: 3.5 mm \pm 0.2
        • Minimum dimension: 3.3 mm
        • Maximum dimension: 3.7 mm
        • Interval: From 3.3 mm to 3.7 mm
        • Possible intermediate values: 3.31 mm, 3.50 mm, 3.69 mm, etc.
      • Mathematical symbols (< less than, > greater than, = equal to) used when determining the interval.

    • Functional Dimensioning:

      • Deviation (interval) permitted in determining dimensions of certain components for proper functioning.
      • Consider minimum and maximum dimensions and possible values of the interval.

    • Functional Dimensioning (cont.):

      • Expressions used to indicate whether or not, or to what extent, a technical object works:
        • Will always work: minimum and maximum dimensions of two components ensure assembly with any required play*.
        • May not always work: assembly not always possible, and even if possible, the object may not work smoothly (e.g., axle diameter too small/large).
        • Will never work: components cannot be assembled, and the object will not work.
        • *Play: space allowed between two components to ensure free movement.
      • Simplified concept: an axle measuring 2.5 mm in diameter can be inserted, without any play, into a hole measuring 2.5 mm in diameter (regardless of the materials).

  • Developments (Prism, Cylinder, Pyramid, Cone) (ST & AST):

    • In ministerial examinations, developments can refer to materials folded into sheets, hollowed-out shapes, or simple objects (without flaps).
    • Lines used:
      • Edge: _
      • Bend line: _ . _ . _ . _

  • Standards and Representations (Diagrams, Symbols) (ST & AST):

    • Different types of motion presented in a design plan, axonometric projection, or isometric projection.
    • Lines used:
      • Visible line (edges and boundaries): _
      • Hidden line (edges and boundaries): _ _ _ _ _ _
      • Centerline: _ . _ . _ . _ . _
      • Dimension line and extension line: ||
    • Line thickness is not evaluated, construction lines are not shown, and students are not required to indicate dimension lines.

Mechanical Engineering

  • Adhesion and Friction of Parts (ST & AST):

    • Adhesion between two surfaces in contact when they could slide but do not.
    • Friction when two surfaces in contact slide or move over each other.

  • Characteristics of Mechanical Links (ST & AST):

    • Link: When two components are assembled and perform a mechanical function that keeps them together.
    • Flexible Link: A link is flexible when there is a flexible linking component or flexible material to ensure the components return to their initial positions if the object works properly.
      *It is wrong to say that the link between a tire and a wheel rim is a flexible link. It is a rigid link because there is no return movement involving these two components. In this case, the material is flexible, but not the link.
    • Partial Link: The linked components must move in relation to one another for the object to work properly. A partial link may also involve a guiding control.
    • Removable/Non-Removable Link: Components that remain assembled in all exploded view drawings are non-removable (fixed links: glued, soldered). Components of a moulded or thermoformed part are considered non-removable.

  • Linking of Mechanical Parts (Degree of Freedom of a Part) (ST & AST):

    • Reference axes (x, y, and z) in the Cartesian plane determine degrees of freedom.
    • Written as subscripts to the right of the letter:
      • T represents freedom of translational movement (Tx, Ty, or T_z).
      • R represents freedom of rotational movement (Rx, Ry, or R_z).
      • Translation occurs along the axes, and rotation occurs around the axes.

  • Guiding Controls (ST & AST):

    • Guiding is the function performed by a component that controls the motion of a moving component, so it follows a specific trajectory.
    • No guiding control in a complete link because it involves movement between components.
    • Rotational Guidance: Between the axle and the hole in the chassis.
    • Helical Guiding: Moving component (screw or nut) undergoes both rectilinear and rotational motion along the same axis.
      • Screw gear system, type I: The screw (driver component) moves inside a nut.
      • Screw gear system, type II: The nut (driver component) moves along a screw.
      • The following are two examples of translational guiding that are not cases of helical guiding:
      • Screw gear system, type III: The screw (driver component) undergoes continuous rotational motion and the nut (driven component) undergoes continuous translational motion. is an irreversible mechanism.
      • Screw gear system, type IV: The nut (driver component) undergoes continuous rotational motion and the screw (driven component) undergoes continuous translational motion. This motion transformation system is an irreversible mechanism.

  • Construction and Characteristics of Motion Transmission Systems (ST & AST):

    • Friction gears, pulleys and belt, gear assembly, sprocket wheels and chain, wheel and worm gear.

  • Speed Changes (ST & AST):

  • Construction and Characteristics of Motion Transformation Systems (ST & AST):

    • Screw gear system, cams, connecting rods, cranks, slides and rotating slider-crank mechanisms, rack-and-pinion drive.
    • When explaining a mechanism, use correct technological language, not everyday language. Go beyond a basic description.
    • Use terms "rotation(al)," "translation(al)," and "helical" when describing motion (e.g., "The rotation of the cam gives the follower translational motion" instead of "The cam turns and the follower moves from left to right.").
    • Identify the type of system (motion transformation or transmission), name the mechanism involved, and indicate movements, characteristics, advantages, and disadvantages.
    • Also, take into account the range of motion of the components.
    • A reversible mechanism can be activated by either the driver or driven component, not just in one direction.
    • Use the terms "driver component," "intermediate component," and "driven component" in explanations.
    • Cam and Roller: Cams push another component to undergo rotational or translational motion. Cams can be different shapes (round, ovoid, curved, etc.) and have centered or eccentric axes of rotation.
    • Only "cam and roller" will be used rather than "cam and follower"
    • When explaining a speed change, do a simple calculation of the ratio between driver and driven components. Intermediate components do not interfere with any speed change in a simple pulley mechanism.

Electrical Engineering

  • Power Supply (ST & AST):

    • Possible concept combinations: Ohm's law and electrical circuits.

  • Conduction, Insulation, and Protection (ST & AST):

    • ST: Covered in Secondary IV; AST: Covered in Secondary III, applied in Secondary IV.
    • Electric current flows through a fuse. When the filament in the fuse melts, the current stops flowing.
    • A resistor opposes the flow of electric current, so conduction, protection, and transformaton of energy are not its electrical function.
    • Concept combinations: Ohm’s law, electrical circuits.

  • Conduction, Insulation, and Protection (Resistance and Colour Code) (ST & AST):

    • Colour code used to determine the value of electrical resistors.

    • A resistor has four bands.

    • COLOUR CODE USED TO DETERMINE THE VALUE OF ELECTRICAL RESISTORS

    • Black: 0; Brown: 1; Red: 2; Orange: 3; Yellow: 4; Green: 5; Blue: 6; Violet: 7; Grey: 8; White: 9; Gold: ; Silver:

    • Multiplier: 1, 10, 10^2, 10^3, 10^4, 10^5, 10^6

    • Tolerance (%):, 20, 5, 10

  • Control (ST & AST):

    • Use correct technological language, not everyday language. Go beyond basic descriptions.
    • Use phrases "opens the circuit" and "closes the circuit" or "allows the current to flow" and "does not allow the current to flow."
    • Example: "The push-button switch closes the electrical circuit and the motor is turned on" rather than "The push-button switch activates the motor" without referring to the circuit.
    • ST: Covered in grade 4; AST: Covered in grade 3 and can be incorporated into grade 4.
    • Concepts that can be tested together include Ohm’s Law and Electrical Circuits.

  • Transformation of Energy (Electricity and Light, Heat, Vibration, Magnetism) (ST & AST):

    • Students could be tested on this concept in conjunction with electrical circuits and the law of conservation of energy.

  • Other Functions (ST & AST):

    • Students can be tested on this concept, but there are no additional clarifications in this regard.

Materials

  • Constraints (ST & AST):

    • Constraints (compression, deflection, shearing, tension, and torsion) are exerted on materials by external forces and tend to deform them.
    • Deformation may not be apparent.
    • Shearing is not solely from cutting blades but occurs during deflection, torsion, or compression when opposite forces in parallel planes create permanent deformation leading to fracture.
      Consider shearing occurs if there is the possibility of fracture.

  • Tension (ST & AST):

    • A body undergoes tension when subjected to a force that tends to stretch it.
    • Tension is primarily associated with a rope because you cannot push or bend it.
    • Pushing on a rope only increases the axial force.
    • When you pull on a rope or twisted wire, its strands stretch out. In this case, the rope or wire is not subjective.to torsion, but the strands undergo rotation because they're located about the line where the force is applied
    • In ministerial examinations, constraints are represented by vectors, and motion is represented by an arrow. One or more vectors may illustrate deflection based on the object.

  • Torsion (ST & AST):

    • A body undergoes torsion when subjected to a force resulting in rotation about an axis or two forces acting in parallel planes.

  • Mechanical Properties and Characteristics of Materials (ST & AST):

    • Defining a material's mechanical properties involves observing the ability to withstand constraint or impact without breaking during normal use.
    • Comparing advantages of different materials to determine suitability for a function.
    • Definitions:
      • Elasticity: Ability to lose shape under constraint and return to original shape.
      • Hardness: Ability to resist scratches, indentation, and deformation.
      • Resilience: Ability to withstand impacts by undergoing deformation without breaking (absorbs impact energy).
      • Stiffness: Ability to retain initial shape under constraints.
      • Fragility: Characteristic of breaking without deformation under constraints. Fragile materials rarely exhibit deformation before breaking (e.g., glass).
      • Ductility and Malleability: Usually associated with metals and manufacturing/shaping processes. Not used to describe components.
        • Ductility: Can be drawn into wires without breaking (e.g., copper).
        • Malleability: Can be flattened or bent without breaking and retains shape (e.g., aluminum foil). Associated with metals that can be laminated or forged.
        • Plasticity: This is not covered in ministerial examinations.

  • Types and Properties (ST & AST):

    • Definitions of properties of materials:

      • Chemical Neutrality: Not chemically active; resists chemicals.
      • Corrosion Resistance: Able to resist corrosive substances (e.g., salts, chemicals).
      • Electrical Conductivity: Ability to conduct an electric current.
      • Heat Resistance: Ability to resist heat while retaining mechanical properties.
      • Lightness: Low-density material.
      • Thermal Conductivity: Ability to transmit heat.

    • Associate materials with their specific properties utilizing a suggestion vocabulary list.

    • Properties of Materials
      ceramics. thermoplastics, thermosetting plastics.

      • Chemical neutrality, Corrosion resistance, Electrical conductivity, Heat resistance, Resilience, Thermal conductivity

  • Modifications of Properties (Degradation, Protection) (ST & AST):

    • Types of treatment preventing degradation apply to all materials (plastics, metals, ceramics, wood).
    • Involves zinc coating (galvanization), rust treatment, paint, varnish, waterproof coating, or additives (pigments, antioxidants).

  • Manufacturing (Characteristics of Drilling, Tapping, Threading, and Bending) (ST & AST):

    • This concept may be tested, but there are no additional clarifications in this regard.

List of Symbols Used in Circuit Diagrams

  • Students must be able to recognize these symbols in a given circuit diagram. However, if they are asked to draw a circuit diagram, they will be given a list of symbols.

Vocabulary Related to the ST Program

  • Mechanical Engineering
    • Characteristics of a Link: Direct or indirect, Translational, Rigid or flexible, Removable or non-removable, Helical , Complete or partial
    • Motion transformation mechanisms: Connecting rod and crank, connecting rod and crank. cam and roller. Rack and pinion, Screw gear system, Slider-crank
    • Motion transmission mechanisms: Friction gear, Cam and roller, Gear assembly, Rack and pinion, pulley and belt, Sprocket wheel and chain, Wheel and worm gear
  • Electrical Engineering
    *Electrical Functions: Conduction, Control, Insulation, Power supply, Protection, Transformation of energy
    *Forms of energy : Chemical, Electrical, Mechanical (vibrational, magnetic and sound), Radiant (light and solar), Thermal
    Types of Circuits: Series, Parallel
  • Materials
    Mechanical properties and - Properties of materials characteristicsofmaterials Ductility Chemical neutrality Elasticity Corrosion resistance Fragility Electrical conductivity Hardness Heat resistance Malleability Lightness Resilience Thermal conductivity Stiffness Types of materials Compression Ceramics Defiection* Thermoplastics Shearing Thermosetting plastics Tension

Vocabulary Related to the AST Program

Mechanical Engineering
Characteristics of a link Direct or Indirect Translational —> < > l— Rigid or Flexible Rotational .Ic k. Removable or Non-removable 1—lelical s&y% Complete or Partial
*Motion transformation mechanisms Motion transmission mechanisms Connecting rod and crankl Slider-crank Friction gear
Electrical Engineering
Electrical Functions Forms of Energy
Conduction Series.