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CURRENT ELECTRICITY — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCURRENT ELECTRICITY2 Marks
Question
How to use Kirchhoff's rules ?
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Answer

→First, label currents in each resistor by symbol I and a directed arrow to indicate that a current flows along the resistor in the direction indicated.
→ If ultimately I is to be positive, the actual current in the resistor is in the direction of the arrow.
→ If I turns out to be negative, the current actually flows in a direction opposite to the arrow.
→ For each source (i.e cell or some other source of electrical power) the positive and negative terminals are labelled as well as a directed arrow with a symbol for the current flowing through the cell.
→The potential difference of the cell $V = V ( P )$ $- V ( N )=\varepsilon- I r$ which is between the positive terminal P and negative terminal N .
→If while labelling the current through the cell goes from P to N then $V =\varepsilon+ Ir$.

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