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 charge flow relate to current?

  Greater flow rate means greater current
• What is true about current in a single closed loop?

  The current has the same value at any point
• What factors affect the current through a component?

  Resistance and potential difference affect current
• How does resistance affect current for a given potential difference?

  Greater resistance results in smaller current
• What characterizes an ohmic conductor?

  Resistance is constant, current is proportional to voltage
• What happens to the resistance of a filament lamp as temperature increases?

  The resistance increases as temperature increases
• How does a diode behave in terms of current flow?

  Current flows in one direction only
• What occurs when electrons flow through a resistor?

  Electrons collide with atoms, transferring energy
• How does current affect resistance in a resistor?

  As current increases, resistance increases
• What happens to resistance in a thermistor at higher temperatures?

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

  Greater length results in greater resistance
• What is the behavior of an LDR in different light conditions?

  Resistance decreases with greater light intensity
• What is the function of the earth wire in a plug?

  It prevents appliances from becoming live
• What is the frequency of mains electricity in the UK?

  50 Hz
• What is the difference between AC and DC?

  AC varies direction, DC flows in one direction
• What does power represent in an electrical context?

  Energy transferred per second
• How is energy transferred from batteries to devices?

  From chemical potential to electrical energy
• What is the role of transformers in the National Grid?

  They change the potential difference
• What is the purpose of step-up transformers?


  To increase potential difference for transmission
• What happens to current in a step-up transformer?

  Current decreases as potential difference increases
• What is static electricity?

  Charge buildup on insulators when rubbed
• What occurs when two insulators are rubbed together?

  Electrons are transferred, creating charges
• What happens during sparking?

  Charge jumps through air to balance charges
• What is the electrostatic force?

  Force of attraction or repulsion between charges
• How does distance affect electrostatic force?

  Closer charges experience a greater force
• What do electric fields represent?

  Regions around charges where forces act
• How do electric field lines behave?

  They point away from positive charges, towards negative

  
• What happens to field lines as charge strength increases?

  More field lines indicate stronger force
• How does proximity to a charge affect force felt?

  Closer to charge means stronger force felt
• What are the characteristics of series circuits?

  • Closed circuit
  • Current follows a single path
  • Current is the same everywhere
  • Total resistance is the sum of individual resistances
• What are the characteristics of parallel circuits?

  • Branched circuit
  • Current splits into multiple paths
  • Total current into a junction equals total current in branches
  • Potential difference is the same across each branch
• What are the safety features of electrical plugs?

  • Live wire: Brown, carries potential difference
  • Neutral wire: Blue, completes the circuit
  • Earth wire: Green/Yellow, prevents appliances from becoming live
• What are the energy transfer methods in appliances?

  • Kinetic energy for motors
  • Thermal energy in kettles
  • Work done equals energy transferred
• What is the function of the National Grid?

  • Links power stations to consumers
  • Transfers electrical power using transformers
  • Step-up transformers increase potential difference
  • Step-down transformers decrease potential difference for safety
• What are the properties of conductors and insulators?

  • Conductors: Electrons can flow, not fixed
  • Insulators: Electrons cannot flow, fixed in place
• What happens during static electricity generation?

  • Insulators rubbed together transfer electrons
  • Positive charge forms on one, negative on the other