Physics CBA2

• What is the unit that charge is measured in?

  Coulombs.
• Unlike charges attract while like charges repel.
• An electric field is a region in which an electric charge experiences a force.
• Electrostatic charging by rubbing involves a transfer of electrons.
• Fires and Explosions can be caused

  by the build up of charges on many

  objects such as planes and petrol

  tankers. If not discharged carefully, a spark

  can start a fire or cause an explosion.
• Toner powder is electrostatically attracted to the latent image, resulting in a visible image of toner particles. A sheet of paper is brought into contact with the drum surface and a charge applied to the back side of the paper attracts the toner image to it.
• $T=$$1/f$period = 1/frequency
• $V=$$λf$wavespeed = wavelength x frequency
• Frequency of waves is affected by the source, while wave speed is affected by the medium.
• Current (Amperes) = Charge (Coulombs) /time (seconds)

  $I=$$Q/t$
• Potential difference (Volts) = resistance (Ohms) x current (Amperes)

  $V=$$RI$
• Potential difference (Volts) = work done (Joules) / amount of charge (Coulombs)

  $V=$$J/C$
• Resistance (Ohms) = (resistivity (Ohms metres) x length (metres)) / cross-sectional area (metres squared)

  $R =$$(ρl)/A$
• The current in a circuit remains the same throughout a series circuit, but splits across branches in a parallel circuit.
• The potential difference in a circuit splits across components in a series circuit but remains the same across branches in a parallel circuit.
• The resistance of a circuit is split across components in a series circuit. What is the formula for calculating overall resistance across multiple components in a parallel circuit?

  $1/R =$$(1/Ra) +$$(1/Rb)$