physics paper 1 topic 2 electricity

• What must be true for electrical charge to flow?

  The circuit must be closed
• What is required for charge to flow in a circuit?

  There must be a source of potential difference
• What does electrical current represent?

  Current is the flow of electrical charge
• How does the rate of flow of charge relate to current?

  Greater flow rate means greater current
• What is the formula relating charge, current, and time?

  $Q =$$I \cdot t$
• What factors affect the current through a component?

  Resistance and potential difference affect current
• What is true about current in a single closed loop?

  The current has the same value at any point
• How does resistance affect current for a given potential difference?

  Greater resistance results in smaller current
• What is the equation for potential difference, current, and resistance?

  $V =$$I \cdot R$
• What happens to current in an ohmic conductor?

  Current is directly proportional to potential difference
• What type of graph represents an ohmic conductor?

  The graph is linear
• How does the resistance of components like lamps and diodes change?

  Resistance changes with the current through the component
• How does temperature affect the resistance of a thermistor?

  Resistance is lower at higher temperatures
• How does the length of a wire affect resistance?

  Greater length results in more resistance
• What happens to the resistance of an LDR in bright light?

  Resistance decreases with greater light intensity
• What is the function of a diode in a circuit?

  Allows current to flow in one direction only
• What does a sharper gradient on a resistance graph indicate?

  It indicates lower resistance
• What type of circuit has only one path for current?

  Series circuit
• What is true about current in a series circuit?

  The current is the same everywhere
• How is total resistance calculated in a series circuit?

  Total resistance is the sum of all resistances
• What is true about components in a parallel circuit?

  Current splits into multiple paths
• What is the relationship between total current and branches in a parallel circuit?

  Total current into a junction equals total current in branches
• What is the potential difference across each branch in a parallel circuit?

  The potential difference is the same across each branch
• What is the mains electricity supply frequency in the UK?

  50 Hz
• What type of current does mains electricity supply?

  Mains electricity is an AC supply
• What happens to AC current?

  It continuously varies from positive to negative
• What is the role of the live wire in a plug?

  It carries the alternating potential difference
• What is the purpose of the earth wire?

  It prevents appliances from becoming live
• What happens if the live wire touches the metal casing?

  The casing becomes live, risking electric shock
• How is power defined in electrical terms?

  Power is energy transferred per second
• What is the relationship between power, current, and voltage?

  Power is directly proportional to current and voltage
• What is the formula for energy transferred in terms of power and time?

  $E =$$P \cdot t$
• What is the formula for energy transferred in terms of charge and potential difference?

  $E =$$Q \cdot V$
• What types of energy can electrical energy be transferred into?

  Kinetic and thermal energy, among others
• What does the power rating of an appliance indicate?

  It shows the power used in Watts
• What is the National Grid?

  A system linking power stations to consumers
• What do transformers do in the National Grid?

  They change the potential difference
• What is the function of a step-up transformer?

  It increases the potential difference
• What is the function of a step-down transformer?

  It decreases the potential difference for safety
• What is a property of all matter related to charge?

  Charge is a property of all matter