Electricity

• What is electric current?

  The rate of flow of charge
• What is a conductor


  a material that allows electrons to flow through it easily
• What is an insulator?


  where electrical current cannot flow freely
• If an object loses electrons it becomes ...


  positively charged
• If an object gains electrons it becomes


  negatively charged
• Small difference in charge:

  low voltage
• High voltage=


  large difference in charge
• What is used to measure potential difference


  voltmeter
• Ammeters are used to measure


  current
• ammeters are always in


  series
• __________ are always in parallel to the component


  voltmeter
• What does a resistor do?

  It reduces the flow of current through the circuit
• How does an LDR work

  As light intensity increases, resistance decreases
• How does a thermistor work?

  As temperature increases, resistance decreases
• A ______ can only let electricity flow one way


  diode
• What is charge measured in


  Coulombs, C
• What is charge denoted by (what is it in an equation)

  Q
• What is the equation for charge

  Charge = Current X Time (Q = It)
• What is potential difference?


  size of difference in charge given by a battery/ used by a component
• what is the full name for amps


  amperes
• Current is measured in


  Amps
• current is denoted with the letter


  I
• A direct current goes


  one direction only
• an alternating current


  constantly reverses
• in science what is time measured in

  seconds
• How does a battery work?


  when a battery is turned on the negative electrons are repelled from the battery's negative side and are attracted to the battery's positive side
• What type of reaction occurs in batterys

  chemical
• Current is the same everywhere in a


  series circuit
• in a series circuit voltage is


  shared
• in a parallel circuit _____ is the same everywhere


  voltage
• Current is shared between branches


  in a parallel circuit
• What is resistance measured in?


  Ohms (Ω)
• what is the equation for voltage

  V=IR (voltage = current x resistance)
• potential difference and current are


  directly proportional
• a device that obeys ohmic law (voltage + current are proportional) is known as what


  ohmic
• Name an ohmic (linear) component

  wire , resistor
• name a non ohmic component


  thermistor, filament lamp, ldr, diode
• how do you work out the total resistance in a series circuit


  Total resistance = R1 + R2 + R3
• how do you work out the total resistance in a parallel circuit


  Total resistance = 1/R1 + 1/R2 + 1/R3
• Describe an LDR graph: (light-dependent resistor)


  As the light intensity increases the resistance starts to decrease. It falls quickly at first but decreases more slowly for higher light intensities. The graph is a curve.