EXAMPLE--A current of 42 amperes flows through three conductors in _parallel_ of 5, 10 and 20 ohms resistance respectively. Find the current in each conductor. SOLUTION: Joint Conductance = 1/5 + 1/10 + 1/20 = 7/20. Supposing the current to be divided into 7 parts, 4 of these parts would flow in the first conductor 2 in the second and 1 in the third. The whole current is 42 amperes. 4/7 of 42 = 24. 2/7 of 42 = 12. 1/7 of 42 = 6. Current in first conductor = 24 amperes. } “ “ second “ = 12 “ } Ans. “ “ third “ = 6 “ } CHAPTER VII ELECTRICAL AND MECHANICAL ENERGY The production of electricity is simply a transformation of energy from one form into another, usually mechanical energy is changed into electrical energy and a dynamo is simply a device for effecting the transformation. Prof. Fessenden truly remarks there are two independent properties of matter--gravity and inertia--and these give two ways of defining force and energy. It should always be remembered that electricity is something real, although not easily defined. And then, too, while it is not matter and not energy, yet under proper conditions (it having the power of doing work) it is convenient to speak of its performances as electric energy. The following questions and answers, although few in number, may present the subject with clearness. =Ques. What is energy?= Ans. Energy is the capacity for doing work. Steam under pressure is an example, a spring bent ready to be released is another form, again, water stored in an elevated tank has capacity for doing work. These examples illustrate _potential energy_, as distinguished from _kinetic energy_. Potential energy may be defined as _energy due to position_, and kinetic energy, as _energy due to momentum_. =Ques. What is matter?= Ans. Matter is anything occupying space, and which prevents other matter occupying the same space at the same time. =Ques. What name is given the smallest quantity of matter which can exist?= Ans. The atom. An atom means that which cannot be cut, scratched, or changed in form and that cannot be affected by heat or cold or any known force; although inconceivably small, atoms possess a definite size and mass. =Ques. What is a molecule?= Ans. A molecule is composed of two or more atoms. =Ques. What is the behaviour of these minute bodies?= Ans. They are perpetually in motion, vibrating with incredible velocities. =Ques. Why at this point are definitions of energy and of matter most useful?= Ans. Because, as stated, all electric action is an exhibition of energy, and energy must act through matter as its medium. =Ques. What is the difference between electricity and magnetism?=[8]