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# RAD150 Chapter 4

Question | Answer |
---|---|

Define electrostatics | study of stationary electric charges |

What is the smallest unit of electric charge? | electron |

What is the fundamental unit of electric charge? | coulomb |

1 coulomb=? | 6.3x10^18 electron charges |

What is Coulomb's Law? | electrostatic force directly proportional to product of charges & inversely proportional to square of the distance F=k(Q1Q2)/d^2 |

Define electrodynamics | study of electric charges in motion |

What is current and how is it measured? | number of electrons flowing; amperes |

1 ampere=? | 1 coulomb of electrons flowing through a conductor per second |

Electromotive force refers to ________ | electric potential |

Define electric potential | the force with which electrons travel |

How is electric potential measured | volts |

1 volt=? | 1 joule per coulomb |

Resistance depends on what 4 factors? | material's conductivity, length, diameter and temperature |

What are the 4 electric states of matter? | insulator, semiconductor, conductor, superconductor |

What is an example of an insulator? | glass, clay, rubber |

What is an example of a semiconductor? | silicon, germanium |

What is an example of a conductor? | copper, aluminum, water |

What is an example of a superconductor? | niobium, titanium |

What is Ohm's Law? | V=IR (voltage=current X resistance) |

What is electric power? How is it measured? | the rate at which energy moves or is used; watts |

1 watt=? | 1 ampere current flowing through 1 volt electric potential |

What is the formula for power? | P=IV |

What are the 3 classifications of magnets? | natural, artificial permanent, electromagnet |

What are the 4 magnetic states of matter? | nonmagnetic, diamagnetic, paramagnetic, ferromagnetic |

Define nonmagnetic & give an example | unaffected by magnets; wood, glass |

Define diamagnetic & give an example | weakly repelled & can't be magnetized; water, plastic |

Define paramagnetic & give an example | weakly attracted to magnets; gadolinium, platinum, aluminum |

Define ferromagnetic & give an example | can be strongly magnetized; iron, nickel, cobalt |

Magnetic force is proportional to _______. | the product of the pole strengths divided by the distance between them |

What is flux density and how is it measured? | magnetic field strength in teslas |

What is a magnetic dipole? | small magnet created by electron orbit |

What is a magnetic domain? | accumulation of atomic magnets with aligned dipoles |

What is magnetic permeability? | the ability of a material to attract lines of magnetic field intensity |

Define induction | the process of making ferromagnetic material into a magnet |

A coil of wire is called a _____. | solenoid |

What did Oersted's experiment reveal? | an electric current is induced if part of a circuit is in a changing magnetic field |

Faraday's Law states that the magnitude of an induced current depends on what 4 factors? | strength of magnetic field, velocity of field moving past conductor, angle between conductor and field, number of turns in conductor |

A coil of wire in a generator is called the _____. | armature |

How does a generator work? | an armature is placed between opposing magnetic poles, mechanically turning the armature induces an electric current within the magnetic field |

What are the 3 types of transformers? | closed-core, shell-type, autotransformer |

What is the transformer law? | the change in voltage is directly proportional to the turns-ratio of the coils Vs/Vp=Ns/Np |

A turns ratio >1 is a _______ transformer, a turns ratio <1 is a _______ transformer. | step-up; step-down |

As voltage in a transformer changes, _____ changes inversely. | current |

Total resistance in a series circuit=? | sum of individual resistances |

Total current in a series circuit=? | current through each element |

Total voltage in a series circuit=? | sum of individual voltages |

Total resistance in a parallel circuit=? | reciprocal of sum of 1/each individual resistance |

Total current in a parallel circuit=? | sum of currents through each element |

Total voltage in a parallel circuit=? | voltage across each element |

A step-up transformer will have _____ voltage and _____ current in the second coil compared to the first. | higher; lower |

A step-down transformer will have _____ voltage and _____ current in the second coil compared to the first. | lower; higher |

Created by:
SCash21