DEFINITION OF PENCIL

PENCIL Pencils have a wooden case with a lead inside made of graphite and clay. The lead is softer or harder depending on the amount of graphite it contains. Types of pencil: HARD PENCIL - identified by letter H - hard and for drawing thin lines - for technical drawing SOFT PENCIL - identified by letter B - soft and for drawing thick lines - for artistic drawing MEDIUM PENCIL - identified by the letters HB - medium hard and for drawing medium lines - for technical or artistic drawing

INTERNATIONAL METRIC SYSTEM

SI BASIC UNITS.

SI DERIVED UNITS.

ENGLISH METRIC SYSTEM

CONVERSION

Tools exam

Exam

Energy

Complete the following test

Energy

Nuclear energy

Nuclear energy

NUCLEAR ENERGY

Main components of a nuclear reactor

Core – It’s the focal point of the reactor, where fuel is contained and nuclear fission reactions take place.

Fuel – Generally, fuel is made of small enriched uranium oxide rods, stacked so as to form cylinders. These rods are wrapped in metal sheathes (steel or zirconium alloy), which allow heat to pass through while blocking the radioactive elements produced by fission.

Moderator – This is a material placed in the reactor to slow down the neutrons produced by fission, in order to reach the most suitable speed allowing the chain reaction to continue.

Heat-transfer fluid (or coolant) - This fluid (liquid or gas) cools the core and carries outside the heat that is produced there. The most commonly used fluid is water.

Control rods – These are rods used in specific materials (silver, indium, cadmium or boron carbide) to control fission inside the core. 

Vessel – The large steel recipient containing the core, the control rods and the heat-transfer fluid.

All the components of the reactor are container in a solid concrete structure that guarantees further isolation from external environment. This structure is made of concrete that is one-metre thick, covered by steel. The most recent reactors sometimes contain two containment structures and are designed to defy all types of accidental events, even the impact of an aircraft.

https://www.youtube.com/watch?v=_UwexvaCMWA

NUCLEAR REACTOR

PARTS OF A WIND TURBINE

MAIN PARTS OF THE WIND TURBINE


There are four main parts to a wind turbine:
- The base
- The tower
- The nacelle
- The blades



The blades

The blades spin at a low rate of about 20-30 rpm. They are made of fiberglass-reinforced polyester.

The nacelle

The nacelle houses a generator and gearbox. As the gearbox spin, the electricity is produced.

The tower

The most common tower design is a white steel cylinder, about 25-100m  tall and 30mt in diameter.  Contains the electrical conduits, supports the nacelle and provides access to the nacelle to maintenance (ladder and lift). It´s made of grey steel.

The base

Bases are made of concrete reinforced with steel bars, supports the whole structure.

LET´S TAKE A LOOK INSIDE A WIND TURBINE:

http://www.top-alternative-energy-sources.com/inside-a-wind-turbine.html

WIND POWER

WIND POWER

http://www.unendlich-viel-energie.de/en/details/browse/7/article/226/functioning-principles-of-a-wind-turbine.html

http://greenpoweroregon.com/green-power/wind-power.aspx

http://www.south-ayrshire.gov.uk/sustainable-development/energy/windpower.aspx

SOLAR ENERGY

HOW DO SOLAR PANEL WORKS?

A solar panel is a device that collects photons or sunlight, which are very small packets of electromagnetic radiation energy, and converts that into heat.

SOLAR POWER PLANTS

These plants use the energy from the sun. There are two main types of installations: photo-thermal and photovoltaic power plants.

Photo-thermal power plant

In this type of power plant, the heat generated by solar radiation produces steam that is used to move the rotor in the generator.

To do this, they use special mirrors, called heliostats,  that reflect sunlight and concentrate it at one point, where it reaches a high temperature.

https://www.youtube.com/watch?v=NDZzAIcCQLQ


Photovoltaic power plant

In these power plants, solar radiation is transformed directly into electricity by panels of photovoltaic cells.
These power plants consist of large areas of photovoltaic panels.