Notes, summaries, assignments, exams, and exercises for Technology for Secondary education

Electronic Components and Their Applications

Applications of capacitors include acting as battery charging and power circuits. The known duration of loading and unloading processes makes them essential in timing circuits.

Diodes and Their Functions

Diodes are active components that allow electric current to pass in one direction and block it in the opposite direction.

Types of Diodes

• Regular: These show the general behavior described above.
• Special: These include additional features that expand the applications of diodes.

Key Applications of Diodes

The most important application is switching, or turning on and off automatically, allowing the passage of current for positive voltages and blocking it for negative voltages. They are also used to protect...

Simple Machines: Fundamental Principles

Lever

A lever is a simple machine that multiplies force. It consists of a rigid bar that pivots around a fixed point called a fulcrum.

• First-Degree Lever

  The fulcrum is located between the effort (force applied) and the resistance (load).

• Second-Degree Lever

  The resistance (load) is positioned between the fulcrum and the effort (force applied).

• Third-Degree Lever

  The effort (force applied) is located between the fulcrum and the resistance (load).

Pulley

A pulley is a wheel with a grooved rim designed to hold a rope or cable. Pulleys are used to change the direction of a force or to gain mechanical advantage.

Hoist (Block and Tackle)

A hoist, also known as a block and tackle, is a system of multiple pulleys combined...

Understanding Energy Sources

Energy sources are resources used to produce heat, light, motion, and more. All energy originates from the Sun, which then derives other forms of energy. The most important forms include mechanical, thermal, nuclear, chemical, and radiant energy.

Classification of Energy

Energy sources are classified into two main categories:

• Primary: Found directly in nature (e.g., wind, water, coal).
• Secondary: Obtained from primary sources (e.g., electricity, gasoline).

Furthermore, energy is categorized by sustainability:

• Renewable: Sources that are renewed in a short period with virtually unlimited reserves.
• Non-renewable: Sources found on Earth in limited, exhaustible quantities.

Electricity Generation

Electricity is a secondary energy...

Intake Manifold Functions

The intake manifold directs inlet gas to the cylinders.

• Otto Carburetor and Single Point: The mixture is created collectively and injected through the throttle body, then distributed to each cylinder. Optimal distribution requires tubes that are as short, straight, and equal in length as possible. A common method involves passing cooling fluid through a duct located in the collector after the throttle butterfly. Warming the mixture increases its volume, which can negatively impact cylinder filling.
• Multipoint Fuel Injection: Fuel is dosed individually for each cylinder and injected at the inlet valve, allowing for better cylinder filling. Variable intake systems adapt the size of the ducts as engine revolutions increase.

Diode Bias: Direct and Reverse

A diode conducts electrical current only when its terminals are connected to the poles of a generator. It is then said that the diode has a bias and is in a state of conduction. If connected backwards, it is reverse biased and is in a state of deadlock, since no current passes.

Commercial Diodes

The symbol of the diode is an arrow indicating the direction in which the current can traverse. Germanium diodes have transparent encapsulation, and the line indicating the negative terminal is red.

Diode Rectification

The current that supplies the power grid, which we can access by connecting an apparatus to a plug, is common alternating current (AC). It is characterized by its polarity, which is continually changing 50 times...

Plastics: Composition, Types, and Manufacturing

Plastics can be defined as a set of synthetic organic materials that are easily moldable using heat and pressure. They are constituted by simple elements through a specific process: Monomers > Polymerization > Macromolecules.

Classification by Structural Composition

• Thermoplastics: These are plastics that can be remolded multiple times.
• Thermosets: These plastics cannot be returned to a moldable state once set.
• Elastomers: Artificial materials obtained by chemical synthesis, known for their elasticity.

Classification by Source

Plastics can be categorized based on their origin:

• Natural Origin: Materials such as wood and cotton.
• Artificial Plastics: Synthesized by chemical procedures and derived from

Fundamental Electrical Concepts

Voltage (V)

Also known as potential difference between two points in a circuit, voltage indicates the difference in electrical energy between those two points. It is measured in volts (V).

Resistance (R)

Resistance of a material indicates its opposition to the flow of electric current. It is measured in ohms (Ω).

Current Intensity (I)

Current intensity expresses the amount of electric charge flowing per second through a circuit section. It is measured in amperes (A).

Ohm's Law

Ohm's Law describes the relationship between voltage, current, and resistance in an electrical circuit. It is expressed as:

• I = V / R (Current = Voltage / Resistance)

Electrical Energy (E)

The electrical energy (E) consumed by a receiver connected...

What are Plastics?

In chemistry and technology, plastics are polymeric organic materials. They are giant molecules formed by carbon atoms linked with hydrogen, oxygen, and to a lesser extent, chlorine, fluorine, nitrogen, or silicon.

Key Properties of Plastics

• Affordable
• Low density
• Waterproof
• Electrical insulators
• Thermal insulators, although not highly resistant to heat
• Resistant to corrosion and weathering
• Resistant to many chemical factors
• Some are recyclable, but not all are biodegradable or easily recycled
• Easy to work with
• Burning some plastics can be highly polluting

Origin of Plastics

Polymers can be classified based on their origin:

• Natural: Occur spontaneously in natural products like cellulose, rubber, and casein.
• Artificial: Industrially obtained

Electricity Generation and Transport Systems

The electromagnetic effect makes it possible to transform movement into electricity. In thermonuclear power stations and fossil fuel plants, radioactive cores or fuels are burned. The energy released from atoms is used in the production of water vapor. This drives a turbine connected to a generator which produces electricity.

Hydropower and Conventional Energy Sources

Electricity is also generated by hydropower from hydraulic energy. Water falls from dams, hitting the pallets of a water turbine connected to a generator that produces electricity. Thermal power plants, thermo-nuclear, and hydro-sources are considered conventional energy sources. They permit obtaining large amounts of electricity at relatively...

Plaster Production Process

Traditional Process

Building a rudimentary orno (kiln) from plaster. Inside, the wood is burned, and the heat dehydrates the stone.

Orno de Cuba

This type of kiln is filled at the top. Any fuel can be used.

Rotary Orno

Any fuel can be used. The material is subjected to constant agitation.

Properties and Applications of Plaster

Tensile and compressive strength depend on the material's nature and the quantity of water used in mixing.

• The Black Plaster: Obtained by the traditional process. It is usually used on plaster walls.
• The White Plaster: Achieves greater purity through finer grinding.

High-quality plaster cast is made from finely ground horn powder.

Glass Manufacturing

Glass is obtained by merging various components. Soda...