CBSE Class 12-science Physics Current Electricity
Ohm's law : Electric current produced through a conductor is directly proportional to the potential difference applied.
Resistance is directly proportional to length and inversely proportional to area cross section of a conductor.
Drift of Electrons and Resistivity
Combination of Resistors
emfs and Internal Resistance
Internal resistance: Offered by the electrolyte and electrodes of a cell when the electric current flows through it.
During discharging: Terminal p.d. V < emf E. V = E-Ir
During recharging: Terminal p.d. V > emf E. V = E+Ir
Combination of Cells
Kirchhoff's Loop Rule: The sum of the potential differences across all the elements around any closed loop must be zero.
Meter bridge cannot be used to measure very low or very high resistance accurately.
Principle of Potentiometer: Potential drop is directly proportional to the length of wire, if uniform thickness and steady current is maintained.
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