ELECTRICAL EFFECTS result from an imbalance of electrical charge, There are two types of electrical charge ,named positive (carried by protons) and negative (carried by electrons). If charges are opposite (unlike), they attract one another, while like charges repel. Forces of attraction and repulsion (electrostatic forces) exist between any two charges particles. Matter is normally uncharged, but if electrons are gained, an object will gain an overall negative charge; if they are removed, it becomes positive. Objects with an over all negative or positive charge are said to have an imbalance of charge, and exerts the same forces as individual negative and positive charges. On this larger scale, the forces will always act to regain the balance of charge. This causes static electricity. For example, lightning is produced by clouds discharging a huge excess of negative electrons. If charges are "free"-in a wire or material that allows electrons to pass through it - the forces cause a flow of charge called an electric current. Some substances exhibit the strange phenomenon of magnetism-which also produces attractive and repulsive forces. Magnetic substances consist of small regions called domains. Normally unmagnetized, they can be magnetized by being placed in magnetic field. Magnetism and electricity are inextricably linked, a fact put to use in motors and generators.
RESISTANCE: For a given voltage, the flow of current depends upon the resistance of a circuit. Resistance is the degree to which a substance resists electrical current. It is measured in ohms.
Electric motor: In a motor, magnetic forces between the winding and permanent produced a rotatory motion.
Electric generator: In a generator, the rotor rotates within the magnetic field of the stator to produce an electric current.
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