2Newton’s Universal Law of Gravitation Every Object in the universe attracts every other object with a force that (for two bodies) is directly proportional to the mass of each body and that is inversely proportional to the square of the distance between them.
12The charge of a normal atom is zero. Charges can be transferred from one object to another by adding electrons.A neutral atom has a zero charge. Adding electrons to a neutral object makes a negative charge object. Taking away electrons from a neutral object makes a positive charged object.
13Principle of conservation of charge: The net charge in an isolated system never changes.
34Voltage act like a force in an electrical system Voltage act like a force in an electrical system. It causes electrons to move.Electrons are negative charged particles found in the outer part of the atom.
35Voltage is the forcelike quantity in electrical systems. Voltage is measured in volts.
37Electric systems are made of (1)Voltage source) (2) conductors (3) Control elements (4) load Voltages source-Battery, electrical plug in, generatorConductors-wiresControl element- switchLoad-appliances, lights, etc
38Electrical circuit is a closed path made by connecting voltage sources, control elements and loads.
51Voltage difference can be created by (1) Chemical means –Chemical energy in dry or wet cells separates the charges to form a positive pole and a negative pole.(2) Magnetic/Mechanical– A coil of wire moving in a magnetic field produces a force on electrical charges that separates the positive and negative charges.(3) Light- light energy that falls on certain materials causes the separation of electrons from their atoms.
52Voltage is measured by using a volt meter, panel meter and a oscilloscope and a multimeter.