Voltage equals electric current x resistance. V=IxR. Yes?
It depends. We assume that R is constant. But it is not always. It may depend on temperature, on the current range involved, the material etc. Filaments for example are notoriously non constant resistors.
Similarly with inductors. The reactance of an inductor is Ohms is proportional to inductance and frequency. But the inductance itself may depend on frequency. For example a mumetal wound core may exhibit a loss of inductance at roughly above low mid frequency band.
For example the Canford inline microphone transformer used on previous Pleiades experiments. By measuring the primary inductance with a digital LCR meter we measure 400mH at high frequencies. But when the meter is emitting a low frequency the measured inductance is much more. In fact the reading is 1.7 Henries.
This affects the sound a lot. For example the effective low cut (Pleiades filter) is less when a microphones is connected.
This also reminds relatively. The mass of a mass depends on speed.
Nature is nonlinear.
Bibliography:
Conceptual Physics - Hewitt
The Feynman Lectures on Physics - Feynmann, Leighton, Sands
Electronics, A Systems Approach - Neil Storey
No comments:
Post a Comment