Electricity

• Nuclear power plants generate electricity by using nuclear reactions to heat water and produce steam, which then drives turbines connected to generators.
• Objects can become charged when electrons move from one

  object to another.
• Electric current flows through conductors such as wires.
• The movement of electrons is called the flow of electric charge or current (I).
• When an object becomes negatively charged, it has more electrons than protons.
• The flow of electric charge is called an electric current.
• In a simple series circuit, there is only one path for the current to follow.
• A circuit is the path that an electric current takes between two points.
• Current is measured in amperes (A) or amps.
• Conventional current always flows from positive (+) to negative (-), regardless of whether it's actually flowing that way.
• A positive charge means that there are fewer electrons than protons.
• Conductors allow charges to pass easily through their atoms.
• An insulator does not allow electric charges to pass easily through its atoms.
• A switch controls whether electricity flows around the circuit.
• An appliance plugged into a socket completes the circuit.
• If the switch is closed, the bulb glows because it heats up due to the electrical energy passing through it.
• A closed switch completes the circuit allowing current to flow.
• Electric potential difference (V) is also known as voltage.
• Potential difference is measured in volts (V).
• Resistance is measured in ohms (Ω).
• Electric potential difference (V) is the energy per unit charge transferred by an electrical source.
• The current flowing through an object depends on how many electrons flow past one point per second.
• Current can be measured using an ammeter.
• You may recall that the atom is made of 3 subatomic

  particles:

  Protons

  Neutrons

  Electrons
• The protons and neutrons

  are located in the nucleus.

  The electrons are in shells

  outside the nucleus.
• Protons have a positive charge (+)

  Electrons have a negative charge (-)

  Neutrons have no electric charge, so they are neutral.

  Atoms are neutral even though they contain electric charges.
• Friction is one cause of electron transfer.

  When two objects rub together, the force of friction can remove

  electrons from one object and cause them to transfer to the

  other object.

  As one object loses electrons, the other object gains them.
• Different substances have

  different abilities to hold

  on to electrons.

  The ability of an object to

  hold on to its electrons is

  called electron affinity.
• This table is called the

  electrostatic series (or

  triboelectric series).

  Objects higher up on the

  chart lose electrons when

  rubbed together with

  objects lower on the

  chart/series, which tend to

  gain electrons.
• The Law of Attraction:

  Particles of opposite charges attract each other.

  The Law of Repulsion:

  Particles with like charges repel each other.
• Coulomb (C) is the measure of

  electric charge.
• Electrical Insulator is a solid,

  liquid or gas that resists or

  blocks the movement of

  electrons.

  Hold on to their electrons

  and do not allow electrons

  to move.

  Conduction is the movement

  or transmission of electrons

  through a substance.

  Conductors allow electrons

  to move and change

  positions.
• Fair conductors allow only some movement of electrons.

  The electrons do not move as freely as in a conductor, but they

  are not held almost in place as they are in an insulator.
• An electroscope is a device

  that detects static electricity

  by using thin metal leaves,

  which separate when charged.

  The study of static electric

  charges is called electrostatics.
• When a negatively charged

  rod is brought near a neutral

  electroscope, the electrons

  in the electroscope are

  repelled by the rod.

  The electrons move down

  into the leaves.

  The leaves are now

  negatively charged, so they

  repel each other.
• Charging by Friction

  Charging by Contact

  Charging by Induction
• Charges can be transferred from one object to

  another when two objects are rubbed together,

  creating friction. This is called charging by friction.

  For example, when the ebonite and fur were

  rubbed together, the fur became positively

  charged and the ebonite rod became negatively

  charged.

  The electrostatic series can be used to determine

  the resulting charges after friction has occurred.
• Charging by contact occurs when electrons transfer

  from the charged object to the neutral object that

  it touches.

  In charging by contact, the neutral substance gains

  the same charge as the charged object that

  touched it.
• Conversely, when a

  positively charged object

  touches a neutral object,

  electrons move from the

  neutral object to the positive

  object and make the neutral

  object more positive.
• Induction is the movement of electrons within a

  substance caused by the nearby charged object,

  without direct contact between the substance and

  object.

  In charging an object by induction, an originally

  neutral substance gains the opposite charge to the

  charged object.