fields and electricity

• What is the overall charge of most objects?

  Zero charge overall
• What is static electricity?

  It is when an object is charged
• What happens when objects with similar charges interact?

  • They repel each other
  • Positive and positive repel
  • Negative and negative repel
• What happens when objects with opposite charges interact?

  • They attract each other
  • Positive and negative attract
• What happens to hair when it is attracted to a wall?

  It has the opposite type of charge
• How does hair become negatively charged?

  It gains electrons
• Why do hairs repel each other?

  They have the same type of charge
• What happens to a balloon when it becomes positively charged?

  Electrons are removed from it
• What is an electric field?

  • A region around a charged particle
  • Exerts force on other charged particles
• How can you tell where an electric field is strongest?

  • Lines are closest together
  • Strongest closest to the atom
• How does a paint sprayer utilize static electricity?

  • Paint becomes charged due to friction
  • Opposite charge on object helps paint stick
• How does photocopying work with static electricity?

  • Insulator in dark, conducts with light
  • Charged plate attracts toner
  • Paper is charged to attract toner
• What is the function of electrostatic precipitators?

  • Stop ash from entering the atmosphere
  • Particles attracted to electrodes
  • Material shaken off for collection
• What natural phenomenon occurs due to highly charged clouds?

  Lightning
• What happens when there is a large voltage difference in the air?

  Air can become conducting
• Why is it dangerous to refuel aircraft?

  Fuel may become charged by friction
• How do aircraft and refueling tanks prevent sparks?

  They are connected by a copper wire
• What is electric current?

  Rate of flow of charge
• What is resistance in an electrical circuit?

  Opposite to the flow of charge
• What does potential difference measure?

  Work done per coulomb of charge
• How is current measured?

  In amperes (amps)
• How is current measured in a circuit?

  Using an ammeter
• How must ammeters be connected in a circuit?

  In series with the component
• What happens to current as brightness increases in a circuit?

  Current also increases
• What is the formula for current?

  $I =$$Q ÷ t$
• What is the current if $Q =$$20 \text{ C}$ and $t =$$5 \text{ s}$?


  $4 \text{ A}$
• What is the current if $Q =$$12 \text{ C}$ and $t =$$3 \text{ s}$?


  $4 \text{ A}$
• What happens to electrons as they move through a conductor?

  They collide with ions, causing resistance
• What happens when electrons collide with ions in a conductor?

  Energy is transferred to the ions
• What is the formula for resistance?

  $R =$$V/I$
• What are the characteristics of series circuits?

  • Same current through each component
  • Total potential difference is shared
  • Total resistance is the sum of resistances
• What are the characteristics of parallel circuits?

  • Same potential difference across each component
  • Total current is the sum of currents
  • Total resistance is less than individual resistances