Some possible Revision Notes for the chapter "Current Electricity" in Class 12 Physics are:
1. Current is the flow of electric charge.
2. The unit of current is Ampere (A).
3. Current is defined as the rate of flow of charge, i.e. I=dQ/dt.
4. Electric potential difference is the driving force for current to flow.
5. Ohm's law states that the current flowing through a conductor is directly proportional to the potential difference across it, provided the physical conditions of the conductor remain the same.
6. Resistance is the property of a conductor by which it resists the flow of current.
7. The unit of resistance is Ohm (Ω).
8. Resistance is inversely proportional to the cross-sectional area of the conductor and directly proportional to its length and resistivity.
9. Resistivity is the intrinsic property of a material by which it opposes the flow of current.
10. The unit of resistivity is Ohm-meter (Ωm).
11. Conductivity is the reciprocal of resistivity and is a measure of the ability of a material to conduct electricity.
12. The unit of conductivity is (Ohm-meter)^-1 (mho/m).
13. Conductors have low resistance and high conductivity whereas insulators have high resistance and low conductivity.
14. Temperature coefficient of resistance is the amount by which the resistance of a conductor changes per unit temperature change.
15. The equation for temperature coefficient of resistance is α= (1/R)(dR/dT), where α is the temperature coefficient of resistance, R is the resistance of the conductor at some temperature T.
16. Electric power is the rate at which work is done or energy is consumed per unit time.
17. The unit of electric power is Watt (W).
18. Electric power is given by P= IV, where I is the current flowing through the conductor and V is the potential difference across it.
19. Joule's law of heating states that the heat produced in a conductor is directly proportional to the square of the current flowing through it and the resistance of the conductor.
20. Kirchhoff's laws are the two fundamental laws governing the flow of current in a circuit.
21. The first law of Kirchhoff's laws, also known as Kirchhoff's junction law, states that the total current entering a junction in a circuit must be equal to the total current leaving the junction.
22. The second law of Kirchhoff's laws, also known as Kirchhoff's loop law, states that the algebraic sum of the potential differences in any closed loop in a circuit is zero.
23. Electric cells are devices that convert chemical energy to electrical energy.
24. A battery is a collection of two or more cells.
25. Internal resistance of a cell is the resistance offered by the electrolyte, electrodes and connecting wires of the cell to the flow of current.
26. The equivalent resistance of a circuit is the resistance that represents the combined effect of all the resistors present in the circuit.
27. Series combination of resistors results in a higher equivalent resistance.
28. Parallel combination of resistors results in a lower equivalent resistance.
29. Wheatstone bridge is a circuit arrangement used to measure unknown resistance.
30. Meter bridge is a circuit arrangement used to measure the unknown resistance of a wire.
31. Potentiometer is a device used to compare emf of two cells or to measure internal resistance of a cell.
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