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| 16300687098 | structure of the atom |  | 0 | |
| 16300724899 | how does the structure of atoms affect the flow of electric current? | all metals have electrons like this, including copper which is used for electrical wiring - these electrons can easily be removed, so a metal wire has many 'free' electrons | 1 | |
| 16300751049 | series circuit | an electric circuit with only one path through which charge can flow |  | 2 |
| 16300761532 | parallel circuit | a circuit that contains more than one path for current flow |  | 3 |
| 16300799467 | circuit symbols |  | 4 | |
| 16300825743 | a voltmeter is connected | in parallel | 5 | |
| 16300858629 | potential difference (voltage) is | the energy transferred per unit charge passed and hence that the volt is a joule per coulomb | 6 | |
| 16300870843 | energy transferred (J) = | charge moved (C) x potential difference (V) | 7 | |
| 16300832323 | an ammeter is connected | in series | 8 | |
| 16300927512 | one coulomb is the | charge that passes a point in a circuit when there is a current of 1 amp for 1 second | 9 | |
| 16300969252 | an electric current as the rate of flow of charge and | the current in metals is a flow of electrons | 10 | |
| 16305975236 | charge (C) = | current (A) x time (s) |  | 11 |
| 16306027121 | electrons will flow when | a potential difference is applied across a component | 12 | |
| 16306082135 | current is conserved at a | junction in a circuit | 13 | |
| 16306243166 | resistance | a way of saying how difficult it is for electricity to flow through something | 14 | |
| 16306117167 | how does changing the resistance change the current? | when the variable resistor in a circuit is used to increase the resistance, the current decreases | 15 | |
| 16306285365 | potential difference (V) = | current (A) x resistance (ohms) |  | 16 |
| 16306318789 | resistors in series | when resistors are connected in series the total resistance of the circuit is increased because the pathway becomes harder for current to flow through R=R₁+R₂+R₃+... | 17 | |
| 16306331608 | resistors in parallel | when resistors are connected in parallel the total resistance of the circuit is less than the resistance of the individual resistors. this is because there are now more paths for the current | 18 | |
| 16306494116 | graph of current against potential difference for a fixed resistor | the two variables are in direct proportion |  | 19 |
| 16306568270 | graph of current against potential difference for a filament lamp |  | 20 | |
| 16306594026 | graph of current against potential difference for a diode |  | 21 | |
| 16306641952 | light-dependent resistor (LDR) has a high resistance in the dark but | the resistance gets smaller when the light intensity increases | 22 | |
| 16306662724 | thermistors have high resistances at low temperatures but | as the temperature increases the resistance decreases | 23 | |
| 16306744065 | circuit | it can easily be adapted to explore resistance in a diode, thermistor or LDR |  | 24 |
| 16306972969 | when there is an electric current in a resistor | there is an energy transfer which heats the resistor | 25 | |
| 16306994490 | electrical energy is dissipated as | thermal energy in the surroundings when an electrical current does work against electrical resistance | 26 | |
| 16307025615 | a model of resistance | 1) as the electrons flow through the lattice of vibrating ions, they collide with the ions. 2) the more collisions they make with the ions, the harder it is for them to pass through, so the higher the electrical resistance 3) when the electrons collide with the ions, they transfer energy to them |  | 27 |
| 16307129337 | reducing resistance | - using wires made from metals with low resistance like copper - thicker wires - cooling metals so that the lattice ions are not vibrating as much | 28 | |
| 16307194292 | pros and cons of the heating effect of an electric current | - useful in an electric heater or a kettle - not useful in a computer or in plugs and wires because it means that useful energy is being transferred from the circuit by heating, and spread out or dissipated | 29 | |
| 16307265808 | energy (J) = | current (A) x voltage (V) x time (s) |  | 30 |
| 16307303676 | power | the energy transferred per second and recall that it is measured in watt | 31 | |
| 16307311078 | power (W) = | energy (J) / time (s) |  | 32 |
| 16307362099 | the power transfer in a component or appliance is | proportional to the potential difference across it and the current through it | 33 | |
| 16307377492 | power (W) = | potential difference (V) x current (A) |  | 34 |
| 16307431053 | power (W) = | current^2 (A) x resistance (ohms) |  | 35 |
| 16307484818 | ow is energy transferred from electrical cells/batteries to motors? | 1) some is transferred by electricity to the motor, where it is transferred to a store of kinetic energy in the fan. 2) some energy will also be transferred by heating the wires, the motor and the surrounding 3) in the end, all the energy will be dissipated by heating, making the surroundings a little warmer (increasing their store of thermal energy) | 36 | |
| 16307530630 | direct current (d.c.) | an electric current that flows in one direction steadily - batteries and cells supply direct current |  | 37 |
| 16307574647 | alternating current (a.c.) | a flow of electric charge that regularly reverses its direction | | 38 |
| 16307600499 | in the UK the domestic supply is | a.c., at a frequency of 50 Hz and a voltage of about 230 V | 39 | |
| 16307636272 | live wire | - brown - connects the appliance to the generators at the power station - at 230 V |  | 40 |
| 16307654919 | earth wire | - green and yellow - connects the metal parts of the appliance to a large metal spike or metal tubing that is pushed into the ground - for safety and is at 0 V if the circuit is correctly connected |  | 41 |
| 16307693300 | neutral wire | - blue - the return path to the power station - if the circuit is correctly connected it is at a voltage of 0 V | | 42 |
| 16307839327 | fuse | an electrical safety device built around a conductive strip that is designed to melt and separate in the event of excessive current | 43 | |
| 16307721970 | why should switches and fuses be connected in the live wire of a domestic circuit? | fuses are always connected in series with the component(s) to be protected from overcurrent, so that when the fuse blows (opens) it will open the entire circuit and stop current through the component(s) | 44 | |
| 16307780654 | dangers of providing any connection between the live wire and earth | - if a fault causes the live wire to touch a metal part, it makes a very low resistance circuit between 230 V and 0 V (the earth). - this causes a very large current to flow to the earth, which heats up the wire and could cause a fire | 45 |
