Electricity

• What happens when two materials are rubbed together?

  A force of friction acts between them, causing electrons to transfer.
• What is the result of electron transfer between two objects when rubbed together?

  One object gains extra electrons, forming a negative charge, while the other loses electrons, forming a positive charge.
• Which particles are able to move during the process of static electricity?

  Only the electrons are able to move.
• What happens to charged electrons in conducting materials?

  The charged electrons would simply flow away.
• How does static electricity behave in insulating materials?

  The charge remains on the object, forming an electrostatic charge.
• What is an example of static electricity in action?

  • A balloon and jumper initially have a neutral charge.
  • Electrons transfer from the jumper to the balloon.
  • The balloon gains a negative charge; the jumper gains a positive charge.
  • The balloon can be attracted to the jumper due to opposite charges.
• What is an electric field?

  An electric field is the area around a charged object where a force can be experienced by another charged object.
• How does the strength of an electric field relate to the charge of the object?

  The stronger the charge of the object, the stronger the field strength and the greater the force experienced.
• What is a radial electric field represented by?

  Field lines passing towards or away from a point.
• How do field lines behave around positively and negatively charged objects?

  Field lines always move away from positively charged objects and towards negatively charged objects.
• What occurs when two electric fields come close to each other?

  Attraction and repulsion can occur, distorting the field lines.
• What characterizes a uniform electric field?

  A uniform field has the same strength throughout, with equally spaced field lines.
• What is a capacitor?

  A capacitor is a component that stores charge.
• What can happen when there is a potential difference between two objects in static electricity?

  Energy can transfer as a spark when the field is strong enough.
• Why is static electricity a risk in the presence of fuel and oxygen?

  An electrostatic spark may provide an ignition source to start a fire.
• How can static electricity be safely managed when refueling aircraft?

  An earth wire between the aircraft hose and the ground can take the charge away safely.
• What are some applications of static electricity?

  • Electrostatic precipitator: Ash is given a negative charge and attracted to positively charged plates.
  • Paint spraying: Charged paint clings to grounded objects.
  • Photocopiers: A light-sensitive plate is given a negative charge to project images.
• What is an electric current?

  An electric current is the flow of charged particles around a circuit.
• How is the size of a current measured?

  The size of a current is measured using an ammeter.
• Where should an ammeter be placed in a circuit?

  An ammeter is always placed in series with the component.
• What does voltage measure in a circuit?

  Voltage measures how much energy is transferred from the electrons to the components.
• How is voltage measured?

  Voltage is measured using a voltmeter, which is placed in parallel to the component.
• What is potential difference?

  The difference in energy between two points in a circuit.
• How does resistance affect current flow?

  If there is more resistance, less current will flow.
• What type of materials are good conductors of electricity?

  Materials with many free electrons are good conductors.
• What happens to current in a series circuit?

  The current has the same value everywhere in a series circuit.
• How is voltage distributed in a series circuit?

  The voltage is shared between components in a series circuit.
• What must happen to the total voltage in a series circuit?

  The total voltage for each component must equal the voltage of the supply.
• What occurs in a parallel circuit regarding current?

  The current will always split and rejoin at a junction in a parallel circuit.
• How does the current behave at a junction in a parallel circuit?

  The total current entering the junction equals the total current leaving the junction.
• What is the potential difference across each branch in a parallel circuit?

  The total potential difference on each branch equals the voltage of the battery.
• What happens if one cell in a parallel arrangement fails?

  If one cell fails, the others will continue to function.
• What is the difference between direct current (DC) and alternating current (AC)?

  DC flows in one direction, while AC flows in both directions and changes direction regularly.
• What is the purpose of a diode in electrical circuits?

  A diode converts AC current from the mains to DC current and ensures current passes in the correct direction.
• What does an oscilloscope measure?

  An oscilloscope measures the voltage and frequency of an alternating current.
• How does a DC supply appear on an oscilloscope?

  A DC supply will show as a horizontal trace because it only flows in one direction.
• What does an AC supply look like on an oscilloscope?

  An AC supply will show a wave because the current is constantly changing direction.
• How do you calculate voltage using an oscilloscope?

  Multiply the amplitude by the y-sensitivity setting.
• What happens when you increase the y-sensitivity dial on an oscilloscope?

  It increases the range of the oscilloscope but reduces its precision.
• What is the purpose of the time-base dial on an oscilloscope?

  The time-base dial adjusts the wavelength of the displayed wave.