electromagnetic oscillograph
Quick Summary
An oscillograph is an instrument used to record time-varying electrical quantities like current and voltage. There are two main types: the electromagnetic oscillograph and the cathode-ray oscillograph.1
The electromagnetic oscillograph operates on the principle of interaction between a permanent magnet's field and a current-carrying coil. Some models use a pen arm attached to the coil to draw a record on moving paper, like in an electrocardiograph. Others, known as light-beam oscillographs, use a mirror attached to the coil to reflect a beam of light onto photographic film, allowing for higher frequency responses. The cathode-ray oscillograph, also called a cathode-ray oscilloscope, uses an electron beam to display these variations on a screen.1
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