ELECTRICITY
- Created by: lawrencejpacey
- Created on: 20-11-17 13:26
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- ELECTRICITY
- Symbols
- Need to be able to draw and understand all of the symbols from the AQA Combined Science: Trilogy specification
- Definitions
- CHARGE - Unit of charge is the COULOMB (C). Equal to the charge of 6.24 x 10 24 electrons
- CURRENT - The rate of flow of charge (C/s). One coulomb of charge flowing in one second is 1 AMPERE
- VOLTAGE / P.D - The electric potential energy per coulomb of charge (J/C).
- SERIES CIRCUIT
- CURRENT remains the same throughout
- VOLTAGE is shared across components
- TOTAL RESISTANCE is equal to sum of resistance across all components
- PARALLEL CIRCUIT
- CURRENT is split between the junctions
- VOLTAGE is the same across the components
- 1/R TOTAL = 1/R of each resistor *NOT NEEDED FOR GCSE*
- Domestic electricity
- Runs on alternating current (a.c.) and had a P.D of 230 V at a frequency of 50 Hz (changes direction 50 times per second)
- In a U.K. plug, the BROWN (LIVE) wire has a P.D. of 230 V and the BLUE (NEUTRAL) wire has a P.D. of 0 V. The EARTH (GREEN AND YELLOW) only carries the current if there is a fault
- The National Grid
- A system of cables and transformers linking power stations to consumers.
- Step-up transformers are used to increase the potential difference then step-down transformers are used to decrease, to a much lower value, the potential difference for domestic use.
- EQUATIONS
- P = IV (Power (W) = Current (A) x Voltage (V)
- P = I2R (Power (W) = Current squared (A) x Resistance (ohms)
- E = Pt (Energy transferred (J) = Power (W) x Time (s)
- E = QV (Energy transferred (J) = Charge (C) x Voltage (V)
- Symbols
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