{"id":1566,"date":"2024-07-12T18:39:55","date_gmt":"2024-07-12T13:09:55","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=1566"},"modified":"2025-07-16T15:06:14","modified_gmt":"2025-07-16T09:36:14","slug":"thevenin-theorem","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ec\/network-theory\/thevenin-theorem","title":{"rendered":"Thevenin Theorem"},"content":{"rendered":"

To develop Thevenin\u2019s theorem, consider figure consisting of two two-terminal networks, N and NL<\/sub> , joined at A and B. \u2018N\u2019 consist of only resistors and independent sources, whereas NL<\/sub> contains arbitrary even non-linear elements. Suppose NL<\/sub> undergoes various changes while N remains unchanged.<\/p>\n

\"Thevenin\u2019s<\/p>\n

To simplify repeated calculations, N is replaced by a simple circuit called its Thevenin equivalent, as shown in fig. (b). The Thevenin\u2019s equivalent consists of a single voltage source Voc in series with a single resistance RTh<\/sub>.<\/p>\n

Thevenin\u2019s theorem states that a linear two-terminal circuit can be replaced by an equivalent circuit consisting of a voltage source Vth in series with a resistor Rth<\/sub>, where Vth is the open-circuit voltage at the terminals and Rth<\/sub> is the input or equivalent resistance at the terminals when the independent sources are turned off.<\/p>\n

Procedure to Calculate Vth<\/sub> :<\/strong><\/h3>\n

Remove the defined load and measure its open circuit voltage as per polarity prescribed. Thus, Vth<\/sub> is the open-circuit voltage across the terminals as shown in fig. (c), i.e., Vth<\/sub> = Voc<\/sub><\/p>\n

Note:<\/strong><\/h5>\n

If a circuit contains dependent sources only, i.e. there is no independent source present in the network then its open-circuit voltage or Thevenin voltage will simply be zero.<\/p>\n

Procedure to Calculate Rth<\/sub> :<\/strong><\/h3>\n

To apply this idea in finding the Thevenin resistance Rth<\/sub>, we need to consider two cases :<\/p>\n

Case-1: When only independent source, i.e., no dependent source in the circuit.<\/strong><\/p>\n

Nullify all the independent source, i.e., (voltage source by short circuit and current source by open circuit) by doing this obtain Req<\/sub> (or Rth<\/sub>) from the open circuit load using resistance reduction method.<\/p>\n

Case-2: When both independent and dependent source are present in the circuit. \"Dependent<\/strong><\/p>\n

Nullify all independent source and keep the dependent source as it is then connect an independent voltage source V\u03b1<\/sub> and current flow through it is I\u03b1<\/sub>. Thevenin resistance is given as Rth<\/sub> = V\u03b1<\/sub>\/I\u03b1<\/sub><\/p>\n

Note:<\/strong><\/p>\n

It often occurs that RTh<\/sub> takes a negative value. In this case, the negative resistance implies that the circuit is supplying power.<\/p>\n

 <\/p>\n

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\n Must Read: <\/strong> What is Network Theory?<\/strong><\/a><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

To develop Thevenin\u2019s theorem, consider figure consisting of two two-terminal networks, N and NL , joined at A and B.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[421,6],"tags":[431,441,442],"class_list":["post-1566","post","type-post","status-publish","format-standard","hentry","category-network-theory","category-ec","tag-dependent-source","tag-independent-source","tag-procedure-to-calculate-rth"],"_links":{"self":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/1566","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/comments?post=1566"}],"version-history":[{"count":0,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/1566\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/media?parent=1566"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/categories?post=1566"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/tags?post=1566"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}