Physics P1 - Electricity

• How does resistance affect the current in a circuit?

  Greater resistance, smaller the current
• What is electric current defined as?

  A flow of electrical charge
• In what units is resistance measured?

  Ohms (Ω)
• What is potential difference also called?

  Voltage
• In what units is potential difference measured?

  Volts (V)
• What is needed for a charge to flow in a circuit?

  A source of potential difference
• How many paths does current have in a series circuit?

  Only 1 path
• How many paths does current have in a parallel circuit?

  More than 1 path
• What does an open switch do to a circuit?

  Turns the circuit off
• What does a closed switch do to a circuit?

  Turns the circuit on
• What is a cell?

  A source of potential difference
• What is a battery?

  2 or more cells in series
• What is unique about how current flows through a diode?

  Current flows in 1 direction only
• What does LED stand for?

  Light emitting diode
• What type of diode emits light?

  LED
• What does an ammeter measure?

  Current
• What does a voltmeter measure?

  Potential difference between 2 points
• What does a variable resistor allow you to do?

  Resistance can be altered
• What is the main function of a fuse in a circuit?

  Breaks the circuit if current too high
• What does a resistor provide in a circuit?

  Resistance
• In the 'Investigating the factors affecting resistance' practical, how does increasing the length of wire affect resistance?

  Resistance increases
• In a series circuit with two resistors, $R_1$ and $R_2$, how do you calculate the total resistance?


  $R_1 +$$R_2$
• How is the total resistance related to the smallest resistance in a parallel circuit?

  Less than the smallest resistance
• What is the current like at all points in a series circuit?

  The same all the way round
• What happens to the potential difference in a series circuit?

  Shared out
• In a parallel circuit, how is the total current related to the currents in separate paths?

  Sum of currents
• What is the potential difference like across each path in a parallel circuit?

  The same
• How does brightness affect the resistance of an LDR (Light Dependent Resistor)?

  Brightness increases, resistance decreases
• How does temperature affect the resistance of a thermistor?

  Temperature increases, resistance decreases
• In what devices are LDRs (Light Dependent Resistors) commonly used?

  Light sensors
• What relationship does an ohmic conductor have between current and potential difference?

  A linear relationship
• What is the relationship between current and potential difference in a filament lamp?

  Non-linear relationship
• What is the relationship between current and potential difference in a diode?

  Current flows in one direction only
• What colour is the live wire in domestic electricity?

  Brown
• What colour is the neutral wire in domestic electricity?

  Blue
• What colour is the earth wire in domestic electricity?

  Green and yellow stripes
• What is the voltage between the live and earth wires in main electricity?

  230V
• What is the frequency of the alternating current in main electricity in the UK?

  50Hz
• When does the earth wire carry current?

  Only if there is a fault
• What are step-up and step-down transformers used for in the National Grid?

  Transfer energy in power stations/homes