Electromagnetic oscillograph
Encyclopedia
Oscillograph
An oscillograph is an instrument for measuring alternating or varying electric current in terms of current and voltage. There are two instruments that are in common use today:*Electromagnetic oscillograph*Cathode-ray oscilloscope...
which measures variations of electric current by having it go through a magnetic coil. Variations in current induce momentum in the coil, which can be directly measured.
The electromagnetic oscillograph was invented by William Duddell
William Duddell
William Du Bois Duddell was a British electro-physicist and electrical engineer. He was privately educated in the UK and France and rose quickly through the prestigious City & Guilds Schools via scholarships...
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Some models utilise a mirror which reflects a beam of light, allowing measurement of minute movements of the coil. Other were fitted with a hand, possibly fitted with a pen to record values.