circuits current basics

• What's is current?

  The rate of flow of charge (e.g.electrons) around a circuit
• When will current flow? (What 2 things needeed)

  If circuit is complete and if there's a potential differencr
• What is the potential difference

  Work done(or energy transferred) by the charge. It's the driving force that pushes the charge around
• What does power supply do

  Current can change direction
• What's the difference between variable and fixed resistor

  Variable an change resistance
• What does ammeter and voltmeter measure

  Ammeter measures current, voltmeter measures pid
• What is the current in metals?


  Flow of electrons
• What is electrical current?


  Rate of flow of charge
• Doubling the potential difference doubles what?


  Current flowing through it
• what is a voltmeter?

  measures potential difference and is connected in parallel with a component
• what is p.d?

  energy transferred per unit charge passed
• ammeter is connected in series with component to measure what?

  current(amps)
• what is power?

  energy transferred per second
• Total current flowing into circuit =

  Total current flowing out

  
• Total current of parallel circuit is the?

  Sum of the current through component of each branch
• When closed circuit includes source of p.d what will there be?

  Current
• What is resistance ?(measured in ohms)

  How difficult it is for current to floe
• Variable resistor changes current. When I increase resistance what happens to current in circuit?

  Decrease
• I'm fixed resistor what is current directly proportional too

  Potential difference

  
• Filament lamps

  • Current flows through makes it heat up ad some energy transferred into thermal energy store of filament
  • P.d increases so tempature(so resistance)increases across filament
  • Lower current flows through filament at high p.d
• What does this graph show?

  Filament

  
• What does resistance of diode depend on?

  Direction of current

  
• Why can current in diode flow in one direction?

  Has high resistance in reverse direction
• Thermistor

  Low tempatures = increased resistance

  High tempatures = lower resistance
• What is thermistor used as because it changes resitance with tempature?

  Tempature sensors or thermostats
• LDR(light dependent resistors) resistance depend on light intensity, what is it used in circuit as?

  Automatically turn on lights at night
• Low light intensity = high resistance

  High light intensity = low resistance
• What is diagram for

  Test resistance in different devices like: filament, diode,thermistor, LDR

  
• Testing a filament light bulb or diode use variable resistor then draw graph of

  Current against p.d
• Testing thermistor vary temp of thermistor and use

  Resistance against temperature
• Testing LDR vary amount of light hitting LDR then draw graph of?

  Resistance against light intensity