P3 - Electricity

• What are the two types of charge?

  Positive and negative
• What happens when a body has equal amounts of positive and negative charge?

  They cancel out, forming a neutral body
• What do like charges do to each other?

  Like charges repel each other
• What do opposite charges do to each other?

  Opposite charges attract each other
• What is the main characteristic of insulators regarding charge?

  Insulators don’t conduct charge
• Why can conductors conduct charge?

  Because their charged particles are delocalised and can flow
• What occurs when two insulators are rubbed together?

  Electrons are transferred from one to the other
• What charge does the object losing electrons acquire?

  A positive charge
• What charge does the object gaining electrons acquire?

  A negative charge
• What happens when conductors are rubbed together?

  Electrons flow in and out, keeping them neutral
• What is sparking in terms of charge?

  Sparking occurs when charge jumps through the air to balance out
• What is electrostatic force?

  It is the force experienced by charged objects, which can be attractive or repulsive
• How does the strength of electrostatic force change with charge and distance?

  Greater charge and smaller separations result in greater force
• What type of force is electrostatic force?

  It is a non-contact force
• Why do charged objects attract small neutral objects?

  Because they induce a charge inside the neutral objects
• What do electric fields represent?

  They represent the direction a positive charge would go

  
• How does the strength of an electric field relate to the charge?

  The stronger the charge, the more field lines there are
• What is required for a current to flow?

  A closed circuit and a source of potential difference
• What does potential difference (p.d.) measure?

  The energy transferred per unit charge
• How is potential difference measured?

  Using a voltmeter placed in parallel across a component
• What does current measure?

  The rate of flow of charge
• How is current measured?

  Using an ammeter placed in series
• What are the differences between series and parallel circuits?

  • Series Circuit:
  • Current follows a single path
  • Current is the same everywhere
  • Total resistance is the sum of all components

  
  

  • Parallel Circuit:
  • Current splits into multiple paths
  • Current may differ in branches
  • Voltage is the same across each branch
• What happens to the graph of current against voltage if resistance is constant?

  The graph is linear for all values of current
• What happens to the graph of current against voltage if resistance changes?

  The graph is nonlinear
• How does resistance change with increasing current?

  Resistance increases as current increases due to electron collisions
• How does temperature affect resistance in normal wires?

  Resistance increases with temperature due to increased atomic vibrations
• How does resistance change in thermistors with temperature?

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

  Greater length results in more resistance
• How does cross-sectional area affect resistance?

  Thinner wires give greater resistance
• How does light intensity affect light-dependent resistors (LDRs)?

  Greater light intensity results in lower resistance
• What is the function of diodes in circuits?

  Diodes allow current to flow freely in one direction
• What is the relationship between power, current, and voltage?

  Power is the product of current and voltage
• What is the formula for energy in terms of charge and potential difference?

  $E =$$Q \times V$
• What is the formula for energy in terms of power and time?

  $E =$$P \times t$
• What are the characteristics of resistors in series and parallel?

  • Series:
  • Total resistance is the sum of individual resistances
  • Current is the same through all components

  
  

  • Parallel:
  • Total resistance is less than the smallest branch
  • Current splits among branches
• What happens to the total resistance in a series circuit?

  The total resistance is the sum of the resistances of each component
• What happens to the total resistance in a parallel circuit?

  The total resistance is less than the smallest branch resistance
• What is the formula for calculating power in terms of current and voltage?

  $P =$$I \times V$
• What is the formula for calculating power in terms of current and resistance?

  $P =$$I^2 R$