circuits 123

• what is a circuit

  • a circuit isa a closed loop which contains a power source that allows electrons to flow through
• what is current

  • current is the measure of flow of electrons around a circuit and is measured in amps using an ameter which is placed in series
• what is potential difference

  potential difference is energy transferred per colubum .Measured across two points using a voltmeter and is placed in parallel.Always flows in a closed circuit.
• On a battery/cell what does the larger line represent and the shorter

  • larger line represents the positive while smaller represent negative
  • electrons flow from positive to negative
• what is the equation for potential difference

  (V)Potential difference(voltage) = (I) current (amps) x R(resistance in ohms)
• How does resistance change with current


  • electrons charge has more energy so when they flow through resistor they collide with the ions in the resistor
  • the current is doing work against resistance which transfers energy to the ions causing them to vibrate more making it more difficult to flow through resistor.
  • leading to resistance increasing and current decreasing
• what is the difference between a series and parallel circuit

  • a series circuit only has one loop
  • a parallel circuit has more than one loop
• why a parallel circuits less reliable than series circuits

  • series circuits are less reliable as if one component breaks the whole circuit breaks
• how is the current and potential difference spilt in series circuit

  the current (amps)is the same everywhere and can be measured using an ammeter in series with the circuit (on the circuit) and resistance (ohms) is equal to the sum of the individual resistances

  the potential difference (volts) is split across components and can be measured using a voltmeter in parallel of the specific component
• how would we find out the voltage of one particular component

  V(potential difference) = current = I(measured in amps) x resistance (r)

  since the current is the same in a series circuit to work out the potential difference of the component we multiply current and resistance of individual component
• how can we work out the total potential difference of a series circuit

  • add the voltage (pd) of individual bulbs
• Why are parallel circuits better than series circuits

  • paralllel circuits contain more than 1 loop meaning each individual component has their own loop and if the component breaks it doesn't;t effect the other components loops and circuit
• how is potential difference shared in a parallel circuit

  • potential difference is the same throughout so the total potential difference of a circuit is equal to the potential difference of each coponent
• how is current shared in a parallel circuit

  in a parallel circuit the current is split between components - how split depends on the individual resistance of each component
• how is resistance shared in a parallel circuit

  • in a parallel circuit the more components added the less total resistance each component faces as it introduces another way for the current to flow
• what is charge

  charge is the measure of the total current thast flows within a certain time period
• how to work out charge

  Q (charge measured in Columbus)= I (current measured in amps) x T(time measured in seconds)
• How does resistant change with temperature

  • normal wires is the same as current
  • Thermistors,hotter temperatures have a lower resistance making them a better conductor while lower temperatures have a higher resistant
• length effect on resistance

  • greater length more resistance and a lower current electrons makle their way through more resistor atoms so harder to get through than shorter
• Diode effect on resistance

  • diode only allows the current to flow in one direction so as it has a high resistance in the opposite direction to stop current from flowing
• Light dependant resistance effect on resistance

  • high light intensity = low resistance
  • low light intensity = high resistance
• what are the three equations for energy

  energy(joule) = power(watt) x time(seconds)

  energy(joule) = current(amps) x voltage x time

  energy (charge x voltage)
• What is an alternating currentand a direct current

  • an alternating current is where the potential difference is constantly changing between positive and negative (charge is constantly changing)
  • a direct current is where the current is the movement of charge of current in one direction
• what is mains supply

  • an alternating current between 230 volts at 50hz
• What is the relationship between current and potential difference and how is it represented on a graph

  • current is directly proportional to p.d as long as the temperature stays constant ( as a higher temp = a higher resistance)
  • due to different resistors have different resistances the steepness of the line varies, a lower resistance has a more a steep line as less p.d kis need to generate a large current
• relationship between current and pd with a filament lamp (non linear graph)

  • as you increase the current you increase the temperature causing more resistance
  • the line gets less steep as less current can flow through
• diode relationship with pd and current

  • diode only allows current to flow in one direction meaning that as you increase the it only goes up like a weird curve idrk
• equations for power

  power = current x potential diff

  power = energy / time

  power = current squared x resistance