Kids Questions & Answers

When you hit a table with a spoon, you hear the noise it makes quite clearly. And you also feel the spoon vibrating. But you may not realise that the noise is really made of those same sorts of vibrations, called sound waves in the air, which enable us to hear the noise. The part of the ear on the …

Despite much research, nobody is completely certain why some people catch colds while others do not. Cold research clinics take volunteers in the hope of finding the cause and cure of the common cold but the strange thing is that while some of the volunteers do catch cold, others simply do not become infected. Their natural resistance to the cold …

When a person blows out a trick birthday candle, it re-ignites itself in a few seconds. The key about a normal candle that is important to a trick candle is the moment after one blows out a candle. Normally, there is a burning ember in the wick that causes a ribbon of paraffin smoke to rise from the wick. That …

A special clear coating is applied to the lenses, either on the front or back of the lens, or sometimes both sides. It’s a transparent coating and can be applied to any colour of lens including clear. The UV-filtering effect, however, is more complex. UV-filtering lenses are coated with special chemicals that allow light to pass through them, but reflect …

As the flagellae of the cells inside the sponge beat the water, a current is set up and water is drawn through the tiny pores into the center of the sponge and then driven out through the hole at the top. Suspended particles of food in the water are caught on the flagellae of the cells and passed back to …

Solar cells use photovoltaic cells to convert sunlight directly into electricity by converting photons (light particles) into electrons (negatively charged particles). Photovoltaic cells are made of semiconductors and silicon, mixed with other material.

A snail is a member of the mollusc family called a gastropod, word which means ‘stomach foot’, and this describes the snail very well. The foot on which the snial moves is also the base of its whole body, and the snail moves by expanding and contracting its muscles, just as we move our muscles. Because the snil’s body is …

Sensor doors use motion sensors or presence sensors. The first are used to activate the door when it detects a moving object, such as a pedestrian or shopping cart. Motion sensors can distinguish between objects moving toward the door or away from it. They use microwave technology, and utilize the Doppler Effect principle. The sensors emit a high frequency microwave …

Ten, nine, eight, seven… zero – lift off. These words sound like music to an astronomer’s ears. As the countdown progresses, the rocket’s engines fire and give it the required push to tear through the atmosphere and escape the earth’s gravitation. These rockets take astronauts and artificial or man-made satellites into space. The satellites are used for communication, weather monitoring …

Pearls are some of the most beautiful gems we know, and very expensive to buy. So it may come as something of a surprise to learn that pearls start off as irritating grains of sand and other substances which get into the soft part of the oyster. The oyster is a mollusc, which means that it has a soft and …