MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Analogue voltmeter. This device is used to measure voltage. Voltage is the potential difference, also called the electromotive force, measured between two points in a flow of electric current. It can be thought of as a measure of the force of the current, and is closely related to the resistance of the circuit and the amount of current. The relative power of batteries is measured in terms of their voltage. This is an analogue voltmeter, using a moving needle to indicate a point on a dial, as opposed to digits on a screen (digital). The voltmeter is connected to the circuit at the black and red points, with the option of connecting to either the 3V or 15V points (with two corresponding scales on the dial). This model, from TickiT, has a negative region on the dial, allowing it to be calibrated to a zero point.
Model release not required. Property release not required.