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# electricity

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

A current will flow through an electrical component only if there is . . . | a VOLTAGE or POTENTIAL DIFFERENCE (p.d.) across its ends. |

The bigger the potential difference across a component . . . | The bigger the CURRENT that flows through it. |

Components resist a current flowing through them. The bigger their resistance . . . | The smaller the current produced by a particular voltage |

The p.d. across a component in a circuit is measured in . . . | VOLTS |

Voltage (p.d.) is measured using . . . | a VOLTMETER connected IN PARALLEL with the component. |

The CURRENT flowing through a component in a circuit is measured using . . . | an AMMETER connected IN SERIES with the component. |

The unit of current is . . . | the AMPERE (AMP) |

A current of 1 A is equal to a charge flowing of . . . | 1 COULOMB per SECOND |

In metals, a current is a flow of charged particles called . . . | ELECTRONS |

In a circuit, we say that Conventional Current always flows from . . . | The POSITIVE terminal of a cell, towards the NEGATIVE terminal. |

In metals, electricity is actually carried by NEGATIVELY charged electrons, which flow from . . . | the NEGATIVE terminal towards the POSITIVE terminal of a cell. |

The behaviour of a component in a circuit can best be studied by plotting . . . | a current-voltage graph. |

A resistor at constant temperature has a constant ratio of . . . | current to voltage. Its graph is a straight line. |

The current-voltage graph for a filament lamp is NOT a straight line. The reason is . . . | Resistance increases as temperature increases. |

A diode is a device which . . . | only allows a current to flow one way through it. |

When components are connected in series . . . | the SAME CURRENT flows through each component. |

The total resistance of components in series is . . . | equal to the SUM of their separate resistances. |

The total potential difference in a series circuit is . . . | shared between the individual compoents. |

If a p.d. of 12 volts is shared between two equal resistances, each one will get . . . | 6 volts. |

If a p.d. of 12 volts is shared between two resistors of 6 ohms and 12 ohms, the bigger resistor will get . . . | 8 volts. ( The smaller one gets 4 volts because it has half the resistance of the other one.) |

When components are connected IN PARALLEL . . . | There is the SAME p.d. across each component. |

The total current in a parallel circuit is equal to . . . | the SUM of the currents through each of the separate components. |

If one lamp is connected to a cell it gets a current of 1 amp. If two identical lamps are connected in parallel (to the same cell) they will get . . . | a current of 1 amp each - that makes the total current 2 amps. |

If one lamp gets a current of 1A from one cell, two lamps joined in series will get . . . | approximately half as much current ( 0.5A) because they have twice as much resistance. |

The p.d. provided by cells connected in series is equal to . . . | the SUM of the p.ds. of each cell separately bearing in mind the direction in which they are connected. |

The resistance of a component is measured in… | OHMS |

Potential difference, current and resistance are related by Ohm's Law which states… | P.d. = current x resistance |

The resistance of a component is calculated by applying Ohm's law as follows: | R = Voltage / current |

If a current of 2A flows in a resistor of resistance 10 ohms, the p.d. across the resistor is . . . | 20 volts |

What is the current when a p.d. of 12v is applied across a 10 ohm resistor? | 1.2 A |

The current through a resistor at constant temperature is . . . | directly proportional to the p.d. across the resistor. |

A lamp converts electrical energy into . . . | light and heat. |

When electric charge flows through a resistor, electrical energy is transferred as . . . | HEAT |

The rate of energy transfer is called . . . | POWER |

Power is measured in watts. 1W is equal to . . . | 1 joule per second |

In an electric circuit, POWER = | P = I V |

Energy transferred = | E = P x t |

CHARGE (coulomb) = | Current x Time |

Metals are good conductors of electricity because . . . | some of their electrons can move freely throughout the metal. |

When two different materials are rubbed together . . | electrons are transferred from one to the other |

Certain materials can be used as electrical insulators. This is because . . . | they do not conduct electricity |

When a substance loses electrons, it becomes . . . | POSITIVELY charged. |

Opposite electric charges will . . . | ATTRACT each other |

Like charges . . . | REPEL each other |

A charged object can be discharged by . . . | connecting it to EARTH with a conductor |

When walking along a nylon carpet with plastic-soled shoes, you may pick up a static charge. This happens because . . . | electrons are transferred by friction from the shoes to the carpet |

When you touch a metal door handle you sometimes receive an electric shock because . . . | a charge passes from your body to earth through the door handle |

Created by:
simonpatel