A battery torch is a portable electrical appliance used for lighting. It has a variety of uses. Doctors use it to examine closely the ears, eyes, noses and mouths of the patients. Do you know how a torch produces light?
A battery torch can be divided into four main parts: the battery, bulb, case and the switch. 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 of two or three dry cells. The body of the torch is fitted with a bulb and dry cells. When the switch of the torch is pressed, the cells get connected to the bulb, and as a result of this the bulb emits light.
The torch produces light by connecting the positive and negative terminals of the dry cells to the bulb. The current passes out at the positive contact through the bulb and returns back via the negative contact, 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, letting the electricity flow out to the bulb. In some other torches, the battery is pushed up so that the positive contact touches the bulb itself. In a battery torch, there is a reflector which reflects back the light to long distances.