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| 16299134937 | how can you produce an electric current using a magnet and conductor? | a changing magnetic field can induce a voltage or potential difference in a wire and this causes a current to flow |  | 0 |
| 16299191420 | the size of the induced potential difference depends on the | - number of turns in a coil of wire - the strength of the magnetic field - how fast the magnetic field changes or moves past the coil | 1 | |
| 16299251506 | a generator | machine that converts mechanical energy into electrical energy - consists of a coil of wire that is rotated inside a magnetic field, as the coil turns, a voltage is induced in the wire -the ends of the coil are connected to slip rings. - electrical contact with an external circuit is made using carbon brushes, which press on the slip rings |  | 2 |
| 16299410244 | commutator | switches over the connections every half-turn of the coil, and so produces a form of direct current | 3 | |
| 16299419019 | dynamo | produces a direct current | 4 | |
| 16299424967 | alternator | produces an alternating current | 5 | |
| 16299456499 | how does a microphone work? | 1) sound waves cause variations in air pressure 2) the pressure variations make a diaphragm vibrate 3) the diaphragm moves a coil of wire backwards and forwards 4) a current is produced | 6 | |
| 16299626970 | how does a loudspeaker work? | 1) the varying current flows through a coil that is in a magnetic field 2) this causes a force on the coil, which moves backwards and forwards as the current varies 3) the coil is connected to a diaphragm, and the movements of the diaphragm produce sound waves | 7 | |
| 16299877776 | step-up transformer | increases the voltage and decreases the current at the same time | 8 | |
| 16299883895 | step-down transformer | makes the voltage lower and the current higher | 9 | |
| 16299916970 | how do transformers work? | 1) a transformer is made using two coils of insulated wire wound onto an iron core - there is no electrical connection between the two coils of wire 2) the alternating current in the primary coil creates a continuously changing magnetic field 3) the iron core of the transformer carries this magnetic field to the secondary coil |  | 10 |
| 16299962438 | transformers only work with | alternating current | 11 | |
| 16300040562 | the potential differences across the coils of a transformer can be worked out using this equation: | potential difference across primary coil / potential difference across secondary coil = number of turns in primary coil / number of turns in secondary coil |  | 12 |
| 16300133093 | power = | current (A) x potential difference (V) |  | 13 |
| 16300196440 | power = | energy transferred (J) / time (s) |  | 14 |
| 16300210830 | power = | current^2 (A) x resistance (ohms) |  | 15 |
| 16300165751 | potential difference across primary coil (V) × current in primary coil (A) = | potential difference across secondary coil (V) × current in secondary coil (A) |  | 16 |
