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Across 4. The negatively charged electrode by which electrons enter an electrical device. 6. A part or aspect of something abstract, especially one that is essential or characteristic. 10. A soft metal core made into a magnet by the passage of electric current through a coil surrounding it. 13. An electric current flowing in one direction only. 14. A person who directs the performance of an orchestra or choir. 15. A stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign. 18. A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction. 21. Valence electron is an outer shell electron that is associated with an atom 23. A thing or substance used for insulation, in particular. 25. An electromotive force or potential difference expressed in volts. 29. The number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table. 30. The central and most important part of an object, movement, or group, forming the basis for its activity and growth. 31. A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power. 32. Belonging to the present time; happening or being used or done now. 33. A thing that generates something, in particular.

Down 1. The unbroken and consistent existence or operation of something over a period of time. 2. The refusal to accept or comply with something; the attempt to prevent something by action or argument. 3. An attachment, connected to the armature of a motor or generator, through which electrical connection is made and which ensures that the current flows as direct current. 4. The SI unit of electric charge, equal to the quantity of electricity conveyed in one second by a current of one ampere. 5. Physical substance in general, as distinct from mind and spirit; (in physics) that which occupies space and possesses rest mass, especially as distinct from energy. 7. A stationary electric charge, typically produced by friction, that causes sparks or crackling or the attraction of dust or hair. 8. A unit of electric current equal to a flow of one coulomb per second. 9. The electron theory, which is now accepted and used to explain the behavior of electricity, states that electric current consists of electron flow and can be defined as a moving charge. 11. Light-emitting diode, a semiconductor diode that glows when a voltage is applied. 12. A stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids. 14. A roughly circular line, route, or movement that starts and finishes at the same place. 16. The rotating coil or coils of a dynamo or electric motor. 17. A piece of iron (or an ore, alloy, or other material) that has its component atoms so ordered that the material exhibits properties of magnetism, such as attracting other iron-containing objects or aligning itself in an external magnetic field. 19. A solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits. 20. The positively charged electrode by which the electrons leave a device. 22. A machine, especially one powered by electricity or internal combustion, that supplies motive power for a vehicle or for some other device with moving parts. 24. Field magnet refers to a magnet used to produce a magnetic field in a device. It may be a permanent magnet or an electromagnet. When the field magnet is an electromagnet, it is referred to as a field coil. 26. An instrument designed to measure electric current, voltage, and usually resistance, typically over several ranges of value. 27. The basic unit of a chemical element. 28. A subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.