Appliances - Kettle

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Most household electric kettles have a heating element inside or in the floor of the kettle. The element has an electrical resistance that causes it to get hot when current flows through it. The switch on the kettle has two electrical contacts. Switching the kettle on, closes these contacts (joins them together) allowing electricity to flow, from the wall socket, through the lead, through the switch, to the element, making it hot and heating the water until it boils.

When the water boils it produces steam – a gas, hot water vapour. Some of this steam is diverted, often through the handle, to a thermostat that switches the kettle off. The thermostat in a kettle is a simple mechanical device that contains a bi-metallic strip that bends when it gets hot and opens (separates) the contacts of the internal electric switch and interrupts the electricity flowing to the heating element.

Modern kettles often stand on a base so that the kettle can be taken away from the electricity supply without having to remove the plug from the wall socket. The underside of the kettle and the base have electric connections. These are designed to prevent you being able to touch them and avoid you getting an electric shock.

The noise a kettle makes whilst it is heating the water is localised boiling on the surface of the heating element.

Electricity

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A home electrical system is an intricate maze of wiring designed to deliver power from a local utility to your home safely and efficiently. Electricity has become an essential part of contemporary life, energizing lights, appliances, heat, air conditioning, televisions, telephones, computers, and many other modern conveniences.

Electricity arrives at your house from your local utility company by a power line or underground though a conduit. Most homes have three-wire service—two hot wires and one neutral.

Throughout the house, one hot wire and one neutral wire power conventional 120-volt lights and appliances. Both hot wires and the neutral wire make a 240-volt circuit for large appliances such as air conditioners and electric furnaces.

An electric meter, monitored by your electric utility company, is mounted where the electricity enters your house.

The main panel is usually right next to or under the meter. This is the central distribution point for the electrical circuits that run to lights, receptacles, and appliances throughout the house.

House Plumbing

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A home’s plumbing system is a network of pipes and devices that bring fresh water into the house, distribute hot and cold water throughout the house and return dirty water and sewage to an external facility.

Water Supply System
The supply system routes municipal water from a pipe buried in the street, through a meter into your house. The pressure usually comes from a remote reservoir on top of a hill or concrete tower, sometimes from an electric pump.

Inside the house, pipes branch out to deliver water to basins, showers, toilets, bathtubs, and appliances such as the geyser, dishwasher, and washing machine. Hot water from the geyser is distributed through a second set of parallel pipes. The pipes are usually out of sight, inside walls and the roof cavity. These pipes and other fittings are typically made of plastic, copper/brass, or galvanized steel, in diameters ranging from 10mm to 40mm. Isolating valves are required should the system spring a leak.

Drain-Waste-Vent System
The drain-waste part of the system carries wastewater from sinks, bathtubs, showers and appliances such as dishwashers and washing machines, and sewage from toilets, and delivers that waste water to an external septic tank or into the public sewer.

There is a vent system connected to the drain-waste piping. This provides a route for sewage gases to escape and also helps the waste water to run freely. The waste water pipes usually run under the floor and the vent pipes (vertical stand-pipes) are usually attached to the outside walls. Since these waste pipes can get blocked, there are ‘rodding points’ provided at suitable junctions where drain-cleaning equipment can be inserted.

Solar Energy

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In a house, the sun’s energy is generally harnessed in two ways; one to heat water, the other to create electricity from photovoltaic cells. Both reduce the electricity used from the main supply but are not normally enough to replace it. The sun’s energy is also influenced by weather and seasons.

Solar Heating of Water

There are many different systems that use the sun’s energy to make hot water. They all involve panels on the roof with many pipes that get hot and heat the liquid inside them. They fall into two categories:

• Direct systems: where water itself flows through the pipes in the panels and into an insulated header tank or directly to the main geyser. It is possible to create a thermo-syphon where the hot water rises to the geyser, but quite often a small electric pump is required. The danger with these systems is when the outside temperature falls below the freezing point of water.
• Indirect systems: which heat an intermediate fluid in a second circuit. Glycol, a fluid that has a low freezing point, is often used. These systems require a special, or intermediate, tank where the hot glycol transfers the heat to the domestic water, and also a circulating pump.

Electricity from Solar Panels

Photovoltaic cells produce electricity from sunlight. This is low voltage, direct current, that can be used directly for LED lights and electronic devices. To generate electricity for the house requires panels with many cells and an inverter to produce an alternating current at the correct voltage. The system often includes batteries which act as a buffer to help stabilise the electricity and can provide electricity after dark.

Architecture

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At its simplest, architecture is the design of buildings, groups of buildings and often the space between buildings. But the scope of architecture goes well beyond just the drawing of plans.

Architecture takes imagination; the ability to order ideas and communicate them clearly; creativity (not necessarily artistic ability); a keen interest in human behaviour, our habitat and the natural environment; and problem solving skills.

What Do Architects Do?
As an architect you are unlikely to spend all your life designing at the drawing board or on the PC using computer -aided -design programmes. In addition to time spent in the office, the architect moves around between various building sites and is in constant contact with clients and the many disciplines involved in the building process. Skills such as computer literacy, site supervision and project management are essential.

Career Opportunities
Architecture can be practiced in a variety of professional capacities:
Registered Professional Architects design and manage projects with the assistance of technologists and draughtsperson. Lecturers at universities are often registered architects and may also be in private practice. Developers often include registered architects in their in-house professional teams.

An experiment involving placing drops of food coloring on a shallow
dish of whole milk, then adding a drop of dish soap.

Milk

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Milk is a highly nutritious beverage that is consumed by millions of people worldwide. It is produced by mammals, such as cows, goats, and sheep, and is typically consumed as a source of protein, calcium, and other essential nutrients.

The production of milk involves several steps, including milking the animals, processing the milk, and packaging it for distribution. In modern dairy farms, cows are milked using specialized machines that extract the milk while minimizing stress and discomfort for the animal.

After the milk is collected, it is typically pasteurized to kill any harmful bacteria and ensure that it is safe for consumption. The milk is then homogenized, which breaks down the fat particles and ensures that they are evenly distributed throughout the milk.

Milk is a versatile ingredient that can be used in a variety of recipes, from baked goods to sauces and smoothies. It is also an important component of many traditional diets around the world.

However, some people may be intolerant or allergic to milk, and may need to seek alternative sources of calcium and protein. Additionally, concerns have been raised about the environmental impact of dairy farming and the welfare of the animals involved.

Overall, milk can be a valuable source of nutrition when consumed in moderation and produced responsibly.

Cheese

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Cheese is a delicious and popular food that has been enjoyed for centuries. It is made by coagulating milk and separating the curds from the whey. The curds are then processed, pressed, and aged to create different varieties of cheese, each with its own unique flavour and texture. Some cheeses, such as blue cheese and Roquefort, are made with the help of mould cultures that give them their distinctive blue or green veins.

Cheese production involves several steps, including milk pasteurization, adding bacterial cultures and rennet to coagulate the milk, and then pressing and aging the cheese. Different types of cheese require different aging times and conditions, which can range from a few days to several years.

There are over 1,800 different varieties of cheese, each with its own distinct flavour, texture, and aroma.

Cheese is a great source of calcium, protein, and other essential nutrients. It can be enjoyed on its own or used as an ingredient in a variety of dishes, from pizza to mac and cheese. However, it's important to consume cheese in moderation as it is high in saturated fat and sodium.

Juice

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Juice is typically made by extracting the liquid from fruits or vegetables using a juicer or blender. The production of juice typically involves several steps, including washing, sorting, and processing the fruits or vegetables.

One of the key benefits of juice is its high nutrient content. Depending on the fruits or vegetables used, juice can provide a variety of vitamins, minerals, and antioxidants that are essential for good health. For example, orange juice is rich in vitamin C, while carrot juice is a good source of beta-carotene.

However, it's important to note that not all juices are created equal. Some commercial juices contain added sugars and preservatives, which can negate many of the health benefits. Additionally, the processing of juice can strip away some of the fibre and other nutrients found in whole fruits and vegetables.

To get the most benefit from juice, it's best to make it at home using fresh, whole ingredients. This allows you to control the quality and ensure that you're getting the full nutritional value. Overall, juice can be a healthy and delicious addition to your diet, as long as it's consumed in moderation and made with care.

Eggs

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Eggs are a versatile and nutritious food that are consumed all over the world. They are a rich source of protein, vitamins, and minerals, and can be prepared in a variety of ways, from boiled and fried to baked and scrambled.

The production of eggs involves raising chickens in specialized facilities called egg-laying farms. The chickens are fed a diet that is specially formulated to promote egg production, and their eggs are collected daily. The colour of an egg's shell depends on the breed of the chicken that laid it. Brown eggs are typically laid by breeds with brown feathers, while white eggs are laid by breeds with white feathers.

Egg-laying farms also follow strict guidelines to ensure that the eggs are safe and free from contaminants. The eggs are cleaned and sanitized before they are packaged and sent to grocery stores and other retailers.

Eggs can also be used for a variety of non-food purposes, such as in hair masks and skincare products due to their high protein content.

Bread

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Bread is one of the oldest and most widely consumed foods in the world. It is a staple in many cultures and is made by combining flour, water, yeast, and salt.

The production of bread involves several steps, including mixing the ingredients, kneading the dough, allowing it to rise, shaping it, and baking it. The type of flour used, and the method of preparation can vary depending on the desired texture and flavour of the bread.

Bread is an important source of carbohydrates and fibre, and can be a nutritious addition to a balanced diet. However, some types of bread, such as those made with refined flour or added sugars, may be less healthy and should be consumed in moderation.

In recent years, there has been a growing interest in artisanal and homemade bread, with many people seeking out breads made with whole grains and natural ingredients. This has led to a resurgence in traditional bread-making techniques and a renewed appreciation for the art of bread-making.

Overall, bread is a versatile and delicious food that has played an important role in human history and continues to be a staple in many cultures around the world.

Fungi

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Fungi are all around us, in the soil, our bodies and the air, but are often too small to be seen with the naked eye. There are 120,000 classified types of fungi. Scientists estimate that there are 2.2 – 3.8 million species in total, including mushrooms, yeast, lichens, rust, and mold.

Fungi are non-motile, heterotrophic (no chlorophyll), unicellular (yeast) or filamentous (fungus), reproduce by means of spores, consist of long thread-like structures known as hyphae that form a mesh-like structure called mycelium.

Some play an important role in the decomposition of organic material and nutrient cycling in nature, while others form symbiotic relationships with plants. Others are plant or animal pathogens or endophytes (living inside a plant). They also serve as a food source for a large variety of organisms, including humans.

They occur in most habitats from the Arctic to Antarctica, from high mountain tops to desert sand. Some even lives in marine and fresh water environments. More than 90% of the estimated 3.8 million fungi in the world are currently unknown to science.

Did you know?
1. A fungus lives in symbioses with algae and this beneficial lifeform is called a lichen.
2. Fungi are in a kingdom of their own but are closer to animals than plants.
3. They have chemicals in their cell walls shared with lobsters and crabs.
4. There is evidence to suggest that yeasts - a type of fungus - were being used to produce the alcoholic drink mead as long ago as 9,000 years ago.
5. Products made from fungi can be used as replacements for polystyrene foam, leather and building materials.
6. DNA studies show that there are thousands of different fungi in a single sample of soil, many of which are unknown and hidden.
7. They are 2-10µm in size.
8. A huge underground fungus that is one of the largest living organisms on the planet. It spanned at least 0.37 square kilometres .It was estimated in 1980 to be at least 1500 years old and weighed at least 100,000 kilograms.
9. Fungi affects every part of your life, what you eat, what you wear, what you do and your mood.
10. Mycorrhizal fungus forms an essential symbiotic relationship with plant roots. Mycorrhizal fungi help tree and shrub roots find water and nutrients. In return, the roots give the fungi carbon, carbohydrates, and other nutrients.
11. Mushrooms and other fungi release an incredible amount of spores into the atmosphere every year, and contributing up to 50 million tonnes of particulates.

Overland Power Transmission and the Electricity Grid

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Have you ever wondered how the lights turn on in your home or how your TV gets power? It all starts from a power station and travels through the electricity grid to reach your home. Let's break it down!
Power Stations: The Source of Energy

At power stations, electricity is generated using various sources like coal, hydro, nuclear, wind, or solar energy. Once electricity is created, it travels a long way to reach our homes. This journey starts with overland power transmission.
Overland Power Transmission: The Superhighway for Electricity

Imagine electricity as a group of cars traveling on a superhighway. To make sure it travels quickly and efficiently over long distances, we use very high voltages. In South Africa, electricity starts its journey at an enormous 800,000 volts (800 kilovolts)! This high voltage helps the electricity move smoothly over long distances without losing much energy.

From Highways to Streets: Bringing Electricity to Your Town/District

Once the electricity reaches your town, it needs to be reduced to a safer level. This happens at substations where the voltage is lowered from 800 kilovolts to 11,000 volts (11 kilovolts). Think of this step as moving from a superhighway to the main streets in your town.

Final Step: Into Your Home

Before electricity enters your home, it needs to be reduced even further to a safe level. Another substation, now in your suburb, lowers the voltage to 240 volts, which is the level we use in our homes. Now, the electricity is ready to power your lights, TV, and all your gadgets safely.

How It All Connects

1. Power Station: Generates electricity.
2. Overland Transmission: Electricity travels at very high voltages (up to 800,000 volts) over long distances.
3. Substation 1: Voltage is reduced to 11,000 volts for the district and industrial consumers. 
4. Substation 2: Voltage is reduced again to a domestic voltage (400-500 volts) within the suburb.

And that's how electricity travels from the power station all the way to your home! It's like a journey from a superhighway to the streets and finally to your doorstep, making sure you have the power you need for all your daily activities. 

From Pump Station to Home: The Journey of Water Pipes

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Water is essential for life, and its journey from the source to your tap is made possible by a fascinating system of engineering. In South Africa, this journey often begins at a pump station, where water from dams, rivers, or reservoirs is treated and pressurized. But how does it get to your home? The answer lies in water pipes and the brilliant STEM professionals who design and maintain them.

Water travels through distribution mains, large pipes that carry water over long distances. These are often made of strong materials like steel or pre-stressed concrete to handle high pressure. At key points, the water branches off into smaller pipes called service lines, which connect directly to homes. Along the way, engineers and technicians use pressure regulators, valves, and meters to ensure water flows smoothly and efficiently.

Since the majority of the pipes are buried underground, the steel pipes are susceptible to external corrosion, for which precautions can be taken. This is a science in itself. Steel water pipes also require internal corrosion resistant linings such as epoxy or cement mortar.

Jobs in this field range from civil engineers, who design the systems, to hydraulic technicians, who maintain the pipes and pumps, and environmental scientists, who monitor water quality. Corrosion engineers ensure long term integrity of installed systems through material selection, coatings and cathodic protection. These roles are critical in South Africa, where ensuring access to clean water and helping communities thrive is a top priority, while preserving our planet's most precious resource.