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# Resistance

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

Define resistance. | Ratio of voltage to current flowing through it |

What is the unit of resistance? | The Ohm |

What is an ohmic conductor? | A conductor whose resistance changes with voltage |

What is a practical resistor? | A resistor of a specific value |

What is another name for a variable resistor? | A rheostat |

What is the total resistance of a set of resistors in series? | The sum |

Name four factors that affect resistance. | Temperature. Length. Cross sectional area. Material of the conductor. |

What is the effect of increasing the temperature of a metallic conductor? | Resistance increases (linearly) |

What is the effect of increasing the temperature of a semi-conductor? | Resistance decreases |

What is a thermistor? | A semi-conductor whose resistance decreases rapidly with an increase in temperature |

What is resistivity? | The ratio of resistance by cross sectional area to length |

What is a wheatstone bridge? | A setup used to determine the resistance of a conductor using three resistors of known resistance |

Two uses of a wheatstone bridge. | Temperature control, fail safes |