Electricity

• current is the flow of electrons through a conductor, measured in amps (A)
• In series, the current is the same throughout but in parallel , the current is split through the branches
• The potential difference tells us the charge needed to drive a current
• In series the total potential difference of the components is equal to the potential difference of the cell
• in parallel circuits, if the components are parallel, the potential difference across each component is the same. if more than one component is in the lower branch, the potential difference across all components is equal to branch above
• the resistance is the potential difference required to drive a current through a component
• an ohmic conductor is a conductor that obeys ohms law. the potential difference is directly proportional to the current
• in a filament bulb, the current is not directly proportional to the potential difference as the filament gets hot leading to a higher resistance
• in a diode, the current only flows in one direction as it has a high resistance in the reverse end. Current increases as potential difference increases in the positive
• In a LDR, as the light intensity decreases, the resistance increases
• in a thermistor, the resistance decreases as the temperature increases
• electrical transfer in a hair dryer

  electrical -> thermal + kinetic
• current from a cell is a DC current
• the mains power supply is AC current
• In the UK, the potential difference in an AC is 230 Volts
• In the UK, the frequency of an AC supply is 50 Hz.
• In the UK, the three core cable is used
• the live wire carries the potential difference from the supply. connects to the fuse
• the neutral wire completes the circuit
• the earth wire is the safety wire. if the appliance becomes live, it melts the fuse, shutting off the current
• step-up transformers increase the potential difference of the supply to a higher level so less energy is lost
• step-down transformers decrease the voltage from the high voltage to 230 Volt which is transferred to homes
• conductors are materials which electrons can flow easily e.g. metals
• insulators are materials that do not allow electrons to pass through them e.g. rubber or plastic
• static electricity is caused by two insulators. when they are rubbed against each other, electrons are transferred from one to the other which leads to a positive charge in one and negative charge in the other
• an electric field is a non-contact force that exists around an electric charge. opposites attract
• the field lines of an electric field is perpendicular to the object