Battery Operated Televisions

Electromagnetism Questions?

The scientist who first discovered a link between electricity and magnetism is a. Hans Oersted b. Albert Einstein c. Michael Faraday d. William Gilbert Which of the following is "not" a characteristic of a step-down transformer? a. There are fewer loops on the secondary coil than on the primary coil. b. It converts alternating current into direct current. c. The voltage of the secondary coil is less than that of the primary coil. d. It is necessary for a doorbell to operate. A step-up transformer is used in a. tape players b. calculators c. doorbells d. television sets The best core for an electromagnet is a. alnico b. iron c. aluminum d. magnetite Which of the following will "not" strengthen an electromagnet? a. increasing the number of loops of wire around the core b. increasing the current flow c. decreasing the voltage d. all of these In order for a motor to run off direct current, it must contain a a. glvanometer b. U-shaped magnet c. primary coil d. commutator The phenomenon in which a current is produced by a changing magnetic field is called electromagnetic a. conduction b. transformation c. induction d. generation Alternating current in the United States has a frequency of a. 30 hertz b. 60 hertz c. 120 hertz d. 240 hertz Almost all of the electricity that people use is produced by a. generators b. motors c. batteries d. transformers A step-down transformer is used in a. doorbells b. X-ray machines c. fluorescent lights d. television sets

Public Comments

1. i dont know who invented it. but it hurts like hell when used on HUMAN SUBJECTS BY MALICIOUS PEOPLE WHO LIED ABOUT THEIR ASSOCIATIONS. .GET OVER YOURSELVES IT HAPPENED AND WILL HAPPEN AGAIN . THERE WAS NO JOE LESI THERE IT WAS TONIA SCOTT AND I WAS HERE AND SAW IT FU K YOUS
2. -Albert Einstein. -It converts alternating current into direct current. -television sets -iron -decreasing the voltage -induction -60 hertz -generators -doorbells
3. You should number your questions. don't know. Look up each one in Wikipedia. b and d. It is used in some old doorbells, but is not "necessary" as there are lots of doorbells without a transformer. Mine has a battery. old CRT type TVs only, of which there are not too many. so I'd say "none" b c d c AC power as distributed in homes is 60 Hz. c. But not all AC in the US is 60 Hz. aircraft, for example, uses 400 Hz a a, b, c, d. Your teacher is looking for not b, as it uses a step up transformer to excite the X-ray tube, but it also has a step down transformer to drive the other electronics. He/she is also looking for not c, as old type fluorescent lights use an inductive ballast. But new ones use a DC-DC converter which includes a transformer. Same for d, it always has a step down transformer, and old CRT types also have a flyback transformer for generating the high voltage for the CRT. Altogether a set of questions that are 20 years old and have not been changed to reflect technology changes in the last 20 years. Ask your teacher why she/he didn't include questions about buggy whips and Model-T automobiles. .