Science 30 January 1999 Grade 12 Diploma Examination

15. Sparks from static electricity pose a hazard in petroleum plants. As two chargedobjects separate, the field strength between themA. decreases in proportion to the square of the distance that separates themB. increases in proportion to the square of the distance that separates themC. decreases in proportion to the distance that separates themD. increases in proportion to the distance that separates them16. Electrical fields resemble magnetic and gravitational fields in that they allA. have the same constantB. cause a compass needle to swingC. exert an attractive and repulsive forceD. are affected by the distance between two sources17. Many oil well pumpjacks operate using electric motors. The electricity must betransmitted over long distances because oil wells are often located in remotelocations. Efficient transmission requiresA. high voltage, low current, and AC linesB. low voltage, high current, and AC linesC. low voltage, high current, and DC linesD. high voltage, high current, and DC lines18. In order for the electric motor of an oil well pumpjack to function, voltage andamperage must be changed. This is accomplished through the use ofA. a resistorB. a generatorC. a transformerD. an AC/DC converter9