Physics

• In an electrical circuit what should the wire be?

  The wire must be a conductor(be able to conduct electricity).When the switch is open, the current flow stops as the circuit is not complete. (Air is an insulator, it will not conduct electricity).
• What is a Conductor

  A material that allows electricity to flow through it easily
• What is an insulator?

  A material that does not allow electricity to flow through it easily
• What is voltage?

  is the amount of elecrtical energy supplied to a circuit ( or a component).
• What supplies Volatage?

  Batteries
• What is voltage measured in?

  Voltmeter
• What is the units of voltage?

  Volt (V)
• What is current?


  is the amount of electricity flowing around a circiut ( or through a component).
• What is current measured using?

  Ammeter
• What unit is for current?

  Ampere (amp) A
• Cell (and Batteries) have a positive + negative terminals. What is this known as?

  Cell polarity
• What is ampere (amp) ?

  The unit of electrical current (represented by the symbol A).
• What is cell polarity?

  The existence of positive and negative terminals in a cell or battery
• What does voltage do?

  causes electrical current to flow
• What is the function of a voltmeter?


  to measure the voltage, or potential variation, between two locations. 
• In a circuit what is current carried by?

  Electrons
• What is electrons?


  Negatively charged particles which can move around an electrical circuit conducting electricity.
• What is Conventional Current?

  The imagined flow of electricity from the positive terminal of a cell or battery to the negative terminals through a circuit.
• What happens to the electrons in Circuit?

  The electrons are repelled (expelled) from the negative terminal of a cell or battery and attracted towards the positive terminal.
• The difference between conductors and insulators?

  Conductors have free electrons (that move around the circuit) and insulators do not have free electrons.
• Whats a series circuit?

  An electrical circuit in which the components are connected in sequence (one after another or side by side)
• Wat happens if a switch is open in a circuit?

  The bulb will not light because the circuit is incomplete. When the switch is closed, both lights will light
• What happens in a circuit between bulbs?

  The total voltage is shared
• What stays the same in a circuit?

  THe current does not change around the circuit. THis means each bulb will have the same brightness
• What is a parallel circuit?

  A circuit which has more than one branch through which electricity can flow.
• Two bulbs connected in parallel ;

  If switch 1 is closed, only the upper bulb will light because current will flow through the upper branch of the circuit only. If both switches (1 and 2) are closed, both bulbs will light. If only switch 2 is closed then only the lower bulb will light.
• In a parallel circuit ;

  each bulb (or branch of the circuit) receives the total voltage from the battery
• In a parallel circuit ;

  The current is shared between the branches (the total current taken from the supply is the sum of the currents through the separate components).
• Where is an ammeter placed when measuring the current through a component?

  A series
• What is resistance?


  THe opposition by a material to the flow of electrical current.
• What the unit of resistance?

  OHM
• Facts about resistance---


  -The bigger the resistance, the lesscurrent will flow

  -Insulators, such as plastics, have a high resistance that prevents electricity flowing through them

  -Conductors, such as metals, have low resistance

  -IF you add more bulbs to a series circuit, the bulbs get dimmer. This is because each time a bulb is added, there is more resistance.
• Equation/ Formula

  Voltage (V), Current (I) and resistance (R)

  V=I x R{ or R =V/I
• Factors affecting the resistance of a wire

  Temperature -- the resistance in a mental wire increases with temperature
• Factors affecting the resistance of a wire

  Material-- the lower the resistance a metal has, the better it is at conducting. This is why copper is commonly used in circuits. Wired often used to demonstrate resistance are constantan ( a mixture of nickel and copper) and nichrome ( a mixture of nickel and chromium).
• Factors affecting the resistance of wire

  Cross-sectional area -- the thicker the wire is, the smaller is its resistance. If the cross-sectional area is doubled, the resistance will halve and so on. The resistance of a wire is inversely proportional to its cross-sectional area
• Variable Resistors


  control current in a circuit by increasing or decreasing the length of resistance wire that the current has to flow through : the longer the wire, the more resistance. They are used in dimmer light switches and volume controls in televisions and radios.
• Household electricity:


  Electricity is relatively easily distributed to homes and businesses. It can be then transferred into other forms of useful energy.
• Useful Energy;


  Heat-- in irons, oven and toasters
• Useful energy

  Movement-- (kinetic) in fans, washing machines and Tumblr dryer motors