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Give me some examples for negative resistance.

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iVenky

iVenky

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What do you mean by negative resistance? Does that mean that the voltage decreases with increase in current?

Give me some practical examples.

Thanks in advance.
 

Dear iVenky
Hi
Yes. if the voltage be increase , the current will decrease. you can see its effect in oscillators or triacs or thyristors or schokly diodes or UJT s or PUT s or tunnel diodes or impet diodes.
the places that have not air and are empty from all things , will have the negative resistance such as vacuum tubes.
Best Wishes
Goldsmith
 
goldsmith said:
Dear iVenky
Hi
Yes. if the voltage be increase , the current will decrease.
Click to expand...
I disagree with your terminology. V = I/R. If you apply a positive voltage to a resistance the current will go into the resistance. If the resistance is negative the current will come out of the resistance. The magnitude is the same in either case, but the direction changes. Like you said, the characteristic is used in oscillators. It sounds like we are doing this guy's homework however.
 

Dear RobG
Hi
See the volt ampere curve of triac or thyristor , please, i said this things according to that. and in triacs , when you increase , the voltage across the MT1 MT2 , at an special time , the current will increase (by decreasing the voltage) . my mean is that .
The current can be create with creating the voltage. but the creation of voltage , will not need to creating the current . consider a simple battery.
Best Wishes
Goldsmith
 

Oh, I see what you mean. Basically a positive sloped input voltage will produce a negative sloped output current. Yes, that is negative impedance.
 

this occurs in several circuit models, as mentioned. The physical interpretation is that there is some way to increase the energy within the system. for example, and amplifier can be used, and will attain energy from an external power supply. In other cases, mechanical systems generate energy which is then transformed into electrical equivalents.

an opamp circuit can easily be designed to measure output current and increase its output voltage as a response. as a model, this could be seen as an amplifier with a series negative resistance on the output. Similar designs can be made to produce a circuit with a negative input resistance.
 

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