chapter 1 review

• gravitational field:

  source- objects with mass

  test bodies: small objects with mass
• gravitational fields example: keeping satellites in orbit, snowboarding down a hill
• electrical field:

  source: objects that are positively/negatively charged

  test bodies: small positively charged objects
• electrical field examples: charges in electrical circuit
• magnetic field:

  source: moving charges in the form of electric current or aligned spins and orbits electrons in a permanent magnet

  test bodies: north end of compass magnet
• magnetic field examples: earths force on compass to tell direction
• DC:

  -each coil connected to individual split ring

  -armature rotates, electric current to each separate coil

  -ALWAYS one direction because of split ring
• DC: output energy= mechanical

  input energy= electrical
• AC:

  -contact between armature and brushes through slip ring

  -slip ring has constant contact with coils, current can change direction
• AC: output energy= electrical

  input energy= mechanical
• voltmeter: always connected in parallel with component being measured
• ammeter: always connected in series with component being measured
• ohmmeter: always connected across components being measured (component must be disconnected from circuit)
• electrical distribution system uses high voltage to reduce energy lost due to heating with in coils
• electrical distribution:

  heat losses- P=I^2R (reduces current, reduces electrical energy that wastes heat in the cables)

  electric power transmitted- P=IV (current must be small for max voltage)