آخر الأخبار

جاري التحميل ...

Cell Terminology

    

       The various terminology related to a cell are,
1. E.M.F. of a cell : the voltage of a cell in an open circuit condition, measured by a very high resistance voltmeter is called e.m.f. of a cell. This is denoted as E, measured in volts. This is shown in the Fig. 1.

2. Internal resistance of a cell : the cell completes path of current from its positive terminal to negative terminal through external circuit. But to complete the closed path, the current flows from negative to positive terminal of cell, internally. The opposition by a cell to a current, when it flows internal to the cell is called the internal resistance of the cell. It is denoted as r and measured in ohms.
       In an equivalent circuit of a cell, its internal resistance is shown in series with that cell. The resistance is shown in series with that cell. The Fig. 2 shows a cell and its internal resistance.

3. Terminal voltage : when an external resistance is connected across the terminals of the cell, the current I flows through the circuit. There is voltage drop 'Ir' across the internal resistance of the cell. The cell e.m.f. E has to supply this drop. Hence practically the voltage available at the terminals of the cell is less than E by the amount equal to 'Ir'. This voltage is called the terminal voltage V. This is shown in the Fig. 3.

      Mathematically, the terminal voltage is given by,

      From external resistance side we can write,

Note: Practically internal resistance of the cell must be as small as possible.
      It can also be observed that on no load i.e. external resistance not connected, the open circuit terminal voltage is same as e.m.f. of the cell, as current I = 0.


about author

hamada i'm hamada rageh electrical power engineer my talent to write articles about electrical engineering and i depend on google books site to write my articles

التعليقات


اتصل بنا

إذا أعجبك محتوى مدونتنا نتمنى البقاء على تواصل دائم ، فقط قم بإدخال بريدك الإلكتروني للإشتراك في بريد المدونة السريع ليصلك جديد المدونة أولاً بأول ، كما يمكنك إرسال رساله بالضغط على الزر المجاور ...

جميع الحقوق محفوظة

your electrical home