- A mechanical assembly of lens elements with the capability to vary its focal length allowing for a closer or farther view of a subject, without changing perspective. Zoom lenses are often described b. Used . y the ratio of their focal lengths from longest to shortest. A 100mm to 400mm zoom may be described as a 4:1 or 4× zoom.
. Used . ...Ampere
- The ampere (symbol: A) is the SI base unit of electrical current equal to one coulomb per second. It is named after André-Marie Ampère, one of the main discoverers of electromagnetism.
Th. Used . e ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would . Used . produce between these conductors a force equal to 2×10–7 newton per metre of length....Recording
- Sound or audio recording is the electrical or mechanical encoding of sound waves and audio signals, usually voice or music for the purpose of reproducing the sounds at a later time. There are two basi. Used . c types of recording, analog in which the signal is variable and continuous, and digital in which the signal is first converted into a binary language.. Used . ...Speaker
- A speaker is a device that converts an electrical signal into the equivalent air vibrations in order to make audible sound.. Used . . Used . ...Discharge Lamp
- A high powered light source produced by an arcing electrical discharge between two electrodes suspended in a glass tube filled with gas, usually high or low pressure sodium gas, xenon, mercury vapor, . Used . or metal halide. This type of illumination is limited to applications such as followspots and projection, where dimming is accomplished by mechanical instruments. Many newer generation mov. Used . ing lights use discharge lamps, dichroic filters and mechanical dimming shutters....