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How can the basic d'arsonval meter movement be used to measure high-amplitude currents?
Wiki User
∙ 14y ago
The basic d'arsonval meter movement be used to measure high-amplitude currents by placing a very low resistance across it.
For instance... Let's say you want a 100 Amp meter. You have a 50 microamp meter with an impedance of 250 ohms. That means you need 99.99995 amps in parallel with 50 microamps across 250 ohms.
(50x10-6)(250) = (99.99995)(x)
X = 0.000125 ohms
Note: At 100 amperes, that resistor is going to dissipate only 1.25 watts, but you are going to need to use fairly substantial cabling, because 0.000125 ohms is a very small value compared to the impedance of even ordinary pieces of wire.
Wiki User
∙ 14y ago
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