Electricity and safety Lesson 28 of the physics course of Mova's primary school: 16 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: the lesson at school .
0 Electricity flows wherever it finds a path to somewhere with a different push, such as the ground, and a human body can be that path. 1 Ordinary water, the water in the bath, in puddles and in sweat, has salts dissolved in it that let electricity through, so wet hands and electrical things must never meet. 2 A bird can sit happily on a power line because it touches only one wire and nothing else, so the electricity has no reason to go through it; a person on a ladder touching a wire and the ground at once gives it a path straight through the body. 3 In a thunderstorm a car is a safe place: lightning runs over the outside of the metal body and into the ground, and it is the metal shell, not the rubber tyres, that protects you. 4 Your own body runs on tiny electric signals too, far too weak to feel, which is why a strong shock from outside can upset your heart. 5 Ordinary water carries electricity because of the salts and minerals dissolved in it, and so does a wet body. 7 Bathrooms have no ordinary sockets, and hair dryers must never be used near a bath. 8 Sockets have little shutters inside the holes that stop things being pushed into the live parts; only a plug opens them properly. 9 The electricity at a socket is strong enough to stop a heart. 10 A bird on one power line is not hurt because there is no path through it to anywhere with a different push, such as the ground. 11 In a thunderstorm, the metal body of a car carries lightning round the people inside and into the ground; the tyres are not what protects them. 12 Lightning often hits the tallest thing around, and it can jump from a lone tree to a person standing under it; in a storm, go indoors. 13 An electric eel has special cells that work like hundreds of tiny batteries in a row, and a large eel can knock a person over. 14 A kite string, especially a wet one, can carry electricity from a power line to the person holding it. 15 Nerves carry messages as tiny electric pulses, and doctors measure the heart's signals with stickers on the chest. 16 The thick earth pin on a plug gives stray electricity a safe path into the ground, so metal kettles and washing machines are earthed. ← previous Batteries, circuits and how electricity flowsnext → Magnets: pulling and pushing without touching↑ back to Physics This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/physics/28-electricity-and-safety/