Current Electricity and Magnetism Science Notes
Electric current (I):
It is the electric charge (Q) flowing through a conductor, such as a metal wire, per unit time (t). Its SI unit is the ampere (A). I = Q/t. 1A = 1 coulomb per second. Electric current is a scalar quantity.
Electro Static (electric) potential
The electric level deciding the direction of flow of electric charge is called electrostatic (electric) potential. Its SI unit is the volt (V). Electrostatic potential is a scalar quantity.
→ It is the difference between the potentials at two points.
→ Dry cell, lead-acid cell, Ni-Cd cell are sources of electricity.
→ Electric circuit (or electrical circuit): A continuous path consisting of conducting wires, a switch or a plug key and other resistances (for example, resistance of an electric bulb) between the terminals of a cell (or a battery) along which an electric current flows is called an electric circuit.
→ To obtain more potential difference, cells are connected in series.
→ If a coil is wound around an iron screw (or an iron rod) and a current is passed through the coil with a cell (or a battery), the screw behaves as a magnet as long as there is current in the coil. The system of the coil and the screw is called an electromagnet. It is an example of magnetic effect of electric current.
→ The working of an electric bell is based on the magnetic effect of electric current.