Topic 10-Electricity and Circuits

• What is the structure of the atom?

  Positively charged nucleus with negatively charged electrons
• What are the relative masses and charges of subatomic particles?

  • Proton: Mass = 1, Charge = +1
  • Neutron: Mass = 1, Charge = 0
  • Electron: Mass = 0 (0.0005), Charge = -1
• What type of circuit is a series circuit?

  A closed circuit
• What is the current behavior in a series circuit?

  The current is the same everywhere
• What type of circuit is a parallel circuit?

  A branched circuit
• How does current behave in a parallel circuit?

  Current splits into multiple paths
• What is the relationship at a junction in a parallel circuit?

  Total current into a junction equals total current out
• What does 'V' represent in electricity?

  Potential difference
• In what unit is potential difference measured?

  Volts
• What does potential difference represent?

  Energy transferred per unit charge
• How is potential difference measured?

  With a voltmeter placed in parallel
• When can there be a voltage across a component?

  In a closed or open circuit
• What happens when there is a potential difference in a closed circuit?

  Current will always flow
• What is the formula for energy transferred?

  Energy = charge moved × potential difference
• What is the symbol for current?

  I
• In what unit is current measured?

  Amps
• What does current represent in a circuit?

  Rate of flow of charge
• How is current measured?

  With an ammeter placed in series
• What is the formula relating potential difference, current, and resistance?

  V = I × R
• What happens with greater resistance in a circuit?

  Current is smaller
• What does a variable resistor do?

  Changes the amount of resistance
• What are the characteristics of series circuits?

  • Components connected end to end
  • Current flows through all components
  • PD is shared across the circuit
  • Total resistance is the sum of individual resistances
• What are the characteristics of parallel circuits?

  • Components connected separately to power supply
  • Current flows through each component separately
  • PD is the same across all branches
  • Total resistance is less than the smallest branch
• How does resistance change with current?

  Resistance increases as current increases
• What happens to electrons in a resistor as current increases?

  Electrons collide with ions, heating the resistor
• How does temperature affect resistance in normal wires?

  Resistance increases as temperature increases
• What is the behavior of a thermistor with temperature?

  Resistance is lower at higher temperatures
• How does length affect resistance?

  Greater length increases resistance
• How does cross-sectional area affect resistance?

  Thinner wires have greater resistance
• How does light intensity affect an LDR?

  Greater light intensity lowers resistance
• What is the behavior of a diode with voltage?

  Allows current in one direction only
• What is the relationship between efficiency and resistance in wires?

  Low resistance means less energy loss
• What are the steps for testing relationships in circuits?

  1. Ensure components do not overheat
  2. Use varied wire resistance
  3. Connect to DC voltage
  4. Measure current and plot graphs
• What is the formula for energy transferred in terms of current, voltage, and time?

  E = I × V × t
• What is power in terms of energy transferred?

  P = E / t
• How is power related to current and voltage?

  Power is directly proportional to current and voltage
• What is the formula for electrical power?

  P = I × V
• What is the formula for power loss in terms of resistance and current?

  P = I² × R
• What is the difference between AC and DC?

  AC varies, DC flows in one direction
• What is the mains supply frequency and voltage in the UK?

  50Hz and 230V