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# Electric Current

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

Define electric current | Electric current is the flow of electric charge. |

What is the unit of electric current? | The Ampere |

How would you measure electric current? | With an ammeter connected in series |

Can you provide another word for potential difference? | Voltage |

How would you measure potential difference? | With a voltmeter connected in parallel |

Define resistance | Resistance is the opposition of the movement of electrons around a circuit |

What is the unit of potential difference? | Volt |

What is the unit of resistance | Ohm |

If a bulb and resistor were connected in a closed circuit, what affect would increasing the resistance have on the bulb? | The bulb would get dimmer - resistance increases so current decreases. |

What is the relationship between current and resistance? | Current is inversely proportional to resistance - as resistance increases, current decreases. |

How would you explain the inverse relationship between current and resistance? | Current is the flow of electric charge but resistance opposes this flow - if one increases, the other must decrease. |

What is the relationship between current and voltage? | Current is directly proportional to voltage - as voltage increases, so too does current. |

Can you explain the difference between two bulbs connected 'in series' and connected 'in parallel'? | Two bulbs connected in series means that they share one common node - all of the current that flows through one bulb must flow through the other. If two bulbs are connected in parallel then they share two common nodes but the current can be different. |

Which do you think would be better in a car - if the bulbs in the headlights were connected in series or in parallel. | In parallel - because the current flowing through each is different, if one bulb blows, the entire circuit is not broken and the other bulb will remain lit. |

Why is it that, if one bulb in a set of Christmas tree lights does not work, the rest of the bulbs will not light up? | Christmas tree lights are connected in series. This means that the current that flows through one bulb must also flow through the next bulb. If one bulb blows, the circuit is broken and no current will flow. |

How would you determine if an unknown material is a conductor of electricity when given a circuit with a bulb? | Set up circuit so that the bulb is lit. Add the unknown material to the circuit. If the bulb remains lit, the material conducts electricity. |

What would a graph of voltage against current look like? | Straight line graph through the origin as voltage and current are directly proportional. |

In a graph of voltage (y-axis) against current (x-axis), how would you interpret the slope? | The slope is equal to resistance - resistance is voltage/current and the slope of a graph is the y-axis/x-axis. |

Can you calculate the current flowing in a circuit when a voltage of 8V is applied and there is a resistance of 2ohms? | 4A |

What is Ohm's Law? | Ohmâ€™s Law states that at constant temperature, the potential difference across a metallic conductor is proportional to the current flowing through it |