Why vaccum tube not follow ohms law
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Answer:
A uniform metre scale has two weights of 10 gf and 8 gf suspended at the 10 cm and 80 cm marks respectively. If the metre scale itself weights 50 gf, find where must the weight be, so that the metre scale stays balanced?
December 30, 2019Archa Tawari
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ANSWER
Let the meter scales is balanced at X cm mark on the scale.
At the balancing condition, Anticlock wise moment must be equal to clock wise moment.
Clockwise moment, about the balancing point is
= moment by 80 gf
=80gf×(80−X)cm
=6400gfcm−80Xgfcm.....(1)
Anticlock wise moment about the balancing point is
= moment by 10 gf + moment by 50 gf
=10gf×(X−10)+50gf×(X−50)
=10Xgfc,−100gfcm+50Xgfcm−2500gfcm.....(2)
At the balancing condition, Clock wise at equilibrium = Anti clock wise moments.
6400−80X=100X−100+50X−2500
6400+2600=140X⇒140X=8000
⇒X=1408000=64.28
Scale is balanced at 64.28 cm from the beginning.
Answer:
Explanation
vacuum tubes do follow Ohm’s Law. Everything electrical obeys Ohm's law. The reason vacuum tubes don't appear to obey the law is that not every consideration takes into account the fact that vacuum tubs have dynamic resistance.
Ohm's law, as applied to "pure" ohmic resistors, requires constant resistance, which no material, no matter how good, exhibits. In the real world, you have to consider that resistance can vary along with voltage and current, and this "complicates" things.