P2

• What is the definition of electrical current

  Electric current is the rate of flow of charge
• What is the unit for charge flow

  Coulombs, C
• What is the unit for current

  Amperes, A
• What is the unit for time

  Seconds, S
• What is the unit for Potential Difference

  Volts, V
• What is the unit for resistance 


  Ohms, Ω
• What is the difference between a series and a parallel circuit

  A series circuit only has one path for the current flow, a parallel circuit has more than one
• What does Ohm's law say?

  The current though an ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor
• What happens to the resistance of a filament lamp as the temperature increases

  As temperature increases, the resistance of a filament lamp increases
• What happens to the resistance of a thermistor as it increases in temperature

  The resistence decreases as the temperature increases
• What happens to the resistance of a LDR as the light intensity increases

  The resistance decreases as light intensity increases
• In what direction can current flow in a diode

  Current can only flow one way through a diode
• Name an application of an LDR

  in sensing circuits such as lights turning on when its dark
• Name an application of a thermistor

  Thermostat
• How does resistance add in series

  R total = R1 + R2
• What happens to current in series/parallel circuits

  Current is the same everywhere in a series circuit

  Current splits in a parallel circuit
• What happens to potential difference in series/parallel circuits

  Potential difference splits in a series circuit

  Potential difference is the same across different paths of a parallel circuit
• What happens to the total resistance of two resistors in parallel

  The net resistance decreases as more components are added
• What do we use to measure potential difference and current

  Voltmeter in parallel and an ammeter in series
• When do certain insulating materials become electrically charged


  When they are rubbed against eachother
• What happens when two electrically charged objects are brought together


  They exert a force on each other
• Two objects with the same charge

  Repel
• Two objects with opposite charge


  Attract
• Where is the electric field strongest

  Close to charged object
• What happens to electrical field as you are away from charged object

  Weakens
• What is the frequency of mains electricity in the UK

  50 Hz (Hertz)
• What is the voltage of mains electricity in the UK

  230V
• What colour is the live wire

  Brown
• What colour is the neutral wire

  Blue
• What colour is the earth wire

  Green and yellow stripes
• What does the live wire do

  Carries the alternating potential difference from the supply
• What does the neutral wire do

  Completes the circuit
• What does the earth wire do?

  Safety wire to stop appliance from becoming live
• What is the Potential difference between earth wire and live wire

  230V
• What is the potential difference of the earth wire

  0 V
• What is the potential difference of the neutral wire

  0 V
• When does the live wire carry a current


  When there is a fault
• What is the symbol for power?

  P
• What is the unit for power

  Watts, W
• What is the symbol for potential difference

  V