Electricity Year 9 Science

• Electrostatic charge


  When objects are rubbed together, one gains electrons and becomes negatively charged, and one loses electrons and becomes positively charged
• Electrostatic charges


  • The charges stay on the object and don't move - they remain static
• Rules for electrostatic charges

  • Like charges repel
  • Unlike charges attract
  • Charged objects attract neutral objects
• Current in a parallel circuit

  If the bulbs are identical, the current will split evenly. If the bulbs are not identical, the current will not split evenly.
• If the lamps are connected in parallel, the electrons are divided between the wires equally between lamps.
• Electric circuit


  A closed-loop that creates electrical components
• Electric static


  An imbalance of electric charges on a surface/material
• Voltage


  A measure of how much energy the electrons gain as they pass through a battery or lose as they move through parts of the circuit
• Potential difference


  Another term for voltage
• Volts (V)


  The unit used to measure voltage
• Voltmeters must be placed in parallel
• Voltage in a series circuit

  Voltage is shared between the components - note they are not always equally shared. It is dependent on the resistance of the load, the higher the resistance, the higher the voltage drop.
• Voltage in series circuits is split
• Voltage in parallel circuits stays the same
• Current in series circuits stays the same
• Current in parallel circuits is split
• Ohm's law


  Describes the relationship between voltage, current and resistance
• Ohm's law can be represented using graphs
• Current


  The number of electrons passing a given point in one second
• Voltage


  The difference in potential energy per unit of charge between two points
• When a circuit is open


  It has a lot of potential energy to do work, but it isn't releasing that energy because the circuit is not complete
• When the circuit is complete


  A current is produced
• The flow of electricity in a circuit

  Is the current
• The potential energy


  Is the voltage
• If the wires became larger

  The voltage would remain the same because the potential energy is not changing, but the current would increase because the flow is larger
• Electromagnetic force


  The repulsive or attractive force between electrically charged particles
• Opposites attract and similarly charged particles repel
• When a conductive metal wire is completed with a battery

  The electrons from the negatively charged side of the battery will be attracted to the positively charged side of the battery at a force equal to the battery's charge
• Without voltage, the electrons will move randomly in all directions
• Voltage is what pushes electrons around the circuit in an orderly manner
• Current


  A measurement of the flow of electrons passing a certain point
• Voltage


  The electrical potential difference between two points and is the driving force within a circuit