electricity

• which poles attract in a magnet

  north and south
• which poles repel in a magnet

  north and north

  south and south
• name the three main subatomic particles

  electron

  proton

  neutron
• the nucleus is made up of what?

  protons and neutrons
• electrons can be transferred however the protons in the nucleus are fixed in position. the electrons are free electrons
• when two insulators are rubbed together, sometimes some electrons are transferred from one to the other.


  the material that loses electrons becomes positively charged

  the material that gains electrons becomes negatively charged
• rub cloth onto a rod. try to pick up some pieces of paper with the rod. what evidence is there that a force is acting between the paper and the rod?

  the paper is attracted to the rod
• is electrostatic force a contact force?

  no
• an electric field


  a region where a charged particle experiences a force. it can be an attractive or repulsive force
• the charge of an object creates an electric field around it
• electric fields can be represented with lines coming out from the charge. the direction of arrows shows which way a positive charge will go
• as the electric charge builds up on an object, and it comes in contact with an object with less electric charge, the extra electrons can "jump" to it
• the extra electrons in an object flow out form where they have built up
• how can we generate static charge

  friction (rubbing two insulators together)
• a van de graaff generator removes electrons to produce a positive charge on its dome
• do you need to touch the dome on a van de graaff to feel the effects?

  no it is a non contact force
• a person touching a van de graaff dome whilst insulated from the ground will become positively charged. the same will happen to their hair. what proves this?

  their hair will rise (repel)
• why does someones hair stand on end when the van de graaff generator is switched on?

  when it is turned on, the generator becomes negatively charged. each hair gains the same type of charge, so they repel and gain electrons
• electrocution is the death by means of electricity
• an electric shock involves electrical harm but doesnt end in death
• what is happening when the van de graaff sparks?


  there is a flow of electrons
• what is the flow of charge called?

  current
• the air is usually an insulator however if the build up of charge is big enough then it will move through the air as a spark
• charge can build up in clouds due to friction between water molecules
• the top of a cloud becomes positively charged, the bottom becomes negatively charged, when enough charge has built up a path will flow to earth, this is lightning. the power in one bolt of lightning is enough to power 32 million homes for a year
• a lightning strike is 5 times hotter than the sun, this causes the air to rapidly vibrate which causes thunder
• what are the symbol, unit and unit symbols of charge

  charge, Q, coulombs, C
• what are the symbol unit and unit symbol for current

  current, I, amperes, A
• what are the symbol unit and unit symbol of time

  time, t, seconds, s
• time = charge/current
• current = charge/time
• charge = current x time
• q = it
• t= q/i
• any current over 0.02 A is capable of producing painful or severe shock
• currents between 0.01 - 0.02 A are lethal
• what is the current in typical household appliances

  0.2
• open switch

  
• closed switch

  
• bulb