Railway Science (Physics-Electric Current and its Effects) (Part-III)

The generation of electric current in a conductor due to a changing magnetic field. Electrical Energy - Energy resulting from the movement of electric charges through a conductor. Magnetic induction - The process by which a magnetic substance acquires magnetic properties temporarily due to the presence of a magnet close to it.

The human body is a conductor because the cells of the body contain various ions which help to conduct electricity. More examples of Conductors - Silver, Copper, Gold, Aluminium, Iron, Steel, Brass, Bronze. Insulators : Materials that do not allow electricity to pass through them. Examples - Plastics, Styrofoam, Paper, Rubber, Glass and Dry air.

It works on the principle of electromagnetic induction. Heating effect of electric current states that when an electric current passes through a conductor it becomes hot and produces heat. Examples - Bulbs, Electric iron, Electric Kettle, Electric Heater, Electric Fuse.

Electromagnets are made of coils of wire with electricity passing through them. A conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions. Metals are commonly used as electrical conductors. An electrode is an electrical conductor used to make contact with a non-metallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air).

Calorimeter is a measuring device used for calorimetry or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Rheostat is a variable resistor that is used to control current. Capacitor is a device for storing electrical energy consisting of two conductors in close proximity and insulated from each other.

Reason - No free ions to conduct electrical charges across the solution. Acids and bases exhibit the property of conducting electricity only when they are taken in aqueous solution in which they can completely ionize and generate free ions.

Electric motor (works on the principle of “Faraday's law of electromagnetic induction) Applications : Fans, washing machines, refrigerators, pumps, and vacuum cleaners. The first electric motor - Invented by Michael Faraday in 1821. A battery stores chemical energy and converts it to electrical energy. A photocell converts light energy into electrical energy.

Resistance (R) is a measure of the opposition to current flow in an electrical circuit. SI unit - ohm (Ω). Parallel combination: When two or more resistances are connected between the same two points, they are said to be connected in parallel combination. The voltage across each resistor in parallel is the same. Equivalent resistance (R) of resistances in parallel is given by:Series combination: When two or more resistances are connected one after another such that the same current flows through them are called as resistances in series. Equivalent resistance (R) of resistances in series is given by: Rₛ= R₁ + R₂+...........Rₙ.

It is a material property of the conductor. It depends only on the nature and temperature of the material and not on the length or density of the material. S.I. unit is ohm-meter (ohm-m) and denoted by rho (ρ). Resistance (R) is a measure of the opposition to current flow in an electrical circuit. S.I. unit - ohm (Ω).

The resistance can be combined in two ways: Series combination - When two or more resistances are joined end to end in series then the total resistance is equal to the sum of the individual resistances. Parallel combination - When two or more resistances are connected across two points in parallel then the reciprocal of their combined resistance is equal to the sum of the reciprocals of the individual resistances.