Tuesday, June 12, 2012

How does a Battery Torch Work?

            A battery torch is a portable electrical appliance used for lighting. Doctors use it to examine closely the ears, eyes, noses and mouths of the patients. We use it to move around in the dark, while other light up areas to search. But do you know how a torch produces light? A battery torch can be divided into four main parts- the battery, bulb, causing and the switch.

Parts of a Battery Torch

            The battery is in the form of dry cells. Dry battery cells such as those in torches, transistors or calculators produce electricity only for a limited time. Most of the torches make use for two or three dry cells. The bulb has a coil, which gets heated up and emits light, when the current is passed through it. The body of the torch holds the battery bulb and the switch. The switch helps to regulate the flow of current. When the switch is pressed, the cells get connected to the bulb, and the bulb emits light.

            The torch produces light when the positive and negative terminals of the dry cells are connected to the bulb. The current passes from the positive terminal through the bulb and returns back via the negative terminal, thus making a complete circuit. When the switch is moved to the on position, a metal piece inside the case touches the positive terminal of the battery, and the circuit is completed.

            In a battery torch, a reflector is placed behind the bulb, which reflects the light over a long distance.