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  • Ohm law

    Mangesh4438

    Member

    Updated: Oct 22, 2024
    Views: 1.0K
    Ohm says i=v/r but at some condition current increases then voltage decreases how is that?
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Replies

  • born_star16

    Member • Sep 23, 2011

    There are some electrical circuits which do not obey Ohm's law. For example, the p-n junction diode. In the p-n junction diode, current does not increase linearly with applied voltage. This happens because the value of "resistance" is not constant as a function of applied voltage. Further, the current only increases significantly if the applied voltage is positive, not negative.
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  • Alienator

    Member • Sep 23, 2011

    Mangesh4438
    Ohm says i=v/r but at some condition current increases then voltage decreases how is that?
    check out the limitations of ohm's law....
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  • magnatron

    Member • Sep 23, 2011

    may be the resistance decreases.. 😛 active devices such as transistors, diodes etc will not obey ohm's law
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  • Oleg Arcadewhich

    Member • Sep 23, 2011

    Mangesh4438
    Ohm says i=v/r but at some condition current increases then voltage decreases how is that?
    Source resistance. When load resistance decreases, current increases, and voltage drop at source side appears. For example:V battery= 14,4VR lamp = 4 OhmR starter = 0.144 OhmR internal of a battery= 0.024 OhmI1=Vbat/(Rlamp+Rbat)=3,57A Vlamp=Vbat-I1*Rbat=14.28VI2= Vbat/(Rstarter+Rbat)=85,7AVstarter= Vbat-I2*Rbat=12,34V
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  • Arp

    Member • Sep 24, 2011

    have you not ever come across varistors or non-linear resistors or lightening arrestors.
    we can have material to follow ohm law only in the range we want by design and then can vary itsbehaviour with voltage.
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  • Ramani Aswath

    Member • Sep 25, 2011

    Mangesh4438
    Ohm says i=v/r but at some condition current increases then voltage decreases how is that?
    If you are talking about real circuits the culprit may be the impedance of the source. The out put voltage of some power supplies could be higher when the load has a high resistance than when it has a low resistance. Ohm's law is still obeyed if one considers the total resistance, that is, source resistance plus load resistance.

    P.S. Sorry, did not notice that Oleg had covered this already.
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  • u_know_who

    Member • Sep 29, 2011

    Ohm's law is created for conductor : The current flow to a conductor at a constant temperature and for a fixed material is proportional to the voltage applied across the conductor. Didode is not that conductor ohm mentioned.
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