W h at is a Flashlig h t A flashlight is a device that makes light It contains batteries that produce electricity to light up the bulb Flashlights are small and lightweight and are easy to carry around Flashlights are particularly useful for seeing outdoors at night Campers use them in their tents and around the campsite Security guards and the police use them to search dark and shadowy places A flashlight gives a single beam of light Some flashlights give a stronger light than other flashlights Kinds of flashlights Flashlights are different shapes depending on how they are used A headlamp is fixed to a headband It points exactly where you are looking and leaves both of your hands free Spelunkers for example use headlamps to explore caves and tunnels underground 6 Spelunkers often have to crawl along narrow dark tunnels A headlamp is the best kind of flashlight to light their way
On your bike Cycle lights are a kind of flashlight too Cyclists should have cycle lights fitted to the front and back of their bicycles Some cycle lights flash on and off so the drivers of motor vehicles can see them more easily When it is dark cycle lights help other people to see the cyclist LED flashlights Most flashlights use a bulb that is a smaller version of a traditional light bulb An LED flashlight uses a light emitting diode which gives a brighter light than a traditional bulb It also uses less energy which means the batteries last longer Flashlights vary in size as well as shape Bigger flashlights use more powerful batteries than smaller flashlights The experiments in this book use a flashlight to explore light shadows and other aspects of science including electricity They will work best in a dimly lit room using a powerful flashlight that gives a strong light 7
T a k i ng a Flashlight A p a r t Flashlights need electricity to work Most have batteries that produce the electricity but the batteries have to be in the correct position for the electricity to flow You will need A flashlight that works 2 Put the batteries back in the flashlight and turn it on Try turning each battery first one way around and then the other Make a note of the positions of the plus and minus ends each time How many ways can you get the flashlight to work 1 Find out how to turn the flashlight on and off Take out the batteries and examine them Each one has a plus sign and a minus sign What happened The bulb lit up when electricity traveled from the batteries through the flashlight and bulb and back to the batteries Electricity needs an unbroken path called a circuit to flow through The circuit is only completed when the plus end of one battery is connected to the minus end of the other battery 8
M a ke YourOwn C i r c u i t You will need 2 pieces of copper wire about 6 inches 15 cm long An AA battery Sticky tape A flashlight bulb 1 Stick a piece of copper wire to each end of the battery 2 Touch the wires to each side of the bulb Does it light up What happened When the wires touched the bulb they completed the circuit Electricity from the battery flowed through the bulb and lit it up Electricity always flows in the same direction from the plus end of the battery to the minus end 9
