What are contact lenses made of? Soft contact lenses are made of an oxygen permeable soft plastic. Hard lenses are made of a plastic like Perspex. There are generally two types of contact lenses: soft and hard. Soft lenses are made of a soft plastic. These days, the plastic used is silicone hydrogel. Silicone hydrogel […]
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What causes thunder? Thunder is caused because the air around a lightning bolt is superheated. Lightning is caused when there is an imbalance in the electrical charge within clouds. During a heavy storm, strong winds circulate through storm clouds. The wind picks up water droplets at the bottom and carries them to the top of
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How does wireless charging work? By sending power from a transmitter to a receiver. Wireless charging is known as inductive charging and it is very common these days. Many of us charge our phones by placing them on a magnetic wireless charging pad. But, how does wireless charging work? It uses something called inductive charging.
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What makes rain smell? A combination of plant oils, bacterial spores, and ozone. Everything always smells very fresh after a rainfall and there is a word for it. Merriam-Webster defines petrichor as, “a distinctive, earthy, usually pleasant odor that is associated with rainfall especially when following a warm, dry period”. The word was invented by
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How does dry cleaning work? Clothes are soaked in a water-free liquid solvent. Dry cleaning is a way of washing clothes without water. At home, all of us wash our clothes in the washing machine using some kind of detergent and water. Inside the washing machine is something called an agitator. This is a drum
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Why do the leaves on a tree change color in the autumn (fall)? The leaves on trees change color in the autumn because the tree breaks down its own chlorophyll. Not all trees lose their leaves. Evergreen trees keep their leaves throughout the year. Trees that lose their leaves in the winter are called deciduous
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Why does smoke inhalation kill people? It reduces the amount of oxygen that the lungs can take out of the air and people die of asphyxiation. House fires are obviously dangerous, but most people who are caught in a fire don’t die from burns. In 2019, there were 3,704 deaths caused by fire in the
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Why are stealth bombers invisible? They are not completely invisible, but they are able to reduce the reflection of radar, infrared, visible light, and radio waves. The first stealth plane was the Lockheed F-117 Nighthawk built in 1981. It was an attack aircraft, not a bomber, but it was the first plane to make use
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What is the difference between snowflakes and hail? Snowflakes are made up of ice crystals and hail is a frozen raindrop. Hail are frozen raindrops. They are generally between 5 mm and 15 cm in diameter. Hail is not as common as snow and can only form in a thunderstorm. For hail to form there
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How does an air fryer work? A fan circulates hot air at high speed which cooks the food. Firstly, let’s look at how food cooks when it is fried. With deep-frying, food is submerged in oil that is heated to between 177 and 191˚C. That seems pretty hot, but it is far below the boiling
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