Series And Parallel

• Current in parallel circuits

  Current is shared between all loops
• Circuits can be a mix of series and parallel parts
• Explanation for lower total resistance in parallel circuits

  Adding more loops increases the options for current flow, making it easier for current to flow down the hill (analogous to lower resistance)
• Advantage of parallel circuits over series circuits

  • If any particular component breaks, the overall circuit is still intact
• All components in truly parallel circuits get their full source potential difference


  If a 12 volt battery is used, all components will have 12 volts across them
• Analogy for current distribution in parallel circuits

  Current flows like water down a hill, taking the path of least resistance
• Parallel circuits

  • Parallel circuits are those with more than one loop and generally each loop will only contain a single component
• In physics terms, the more loops added in parallel, the lower the overall resistance will be, even if those loops contain big resistors
• Total current in a circuit with two loops

  Will always add up to the total current of the circuit, in this case, 4 amps
• Resistance in parallel circuits

  The more components added in parallel, the lower the total resistance of the circuit
• Current distribution in parallel circuits


  Depends on the resistance of individual components, with loops of greater resistance taking a lower share of the current
• Total resistance in a series circuit


  Sum of individual resistances of each component
• Calculating current in a series circuit using total resistance

  Dividing potential difference by total resistance (Ohm's Law)
• Calculating voltage across another component in a series circuit

  Subtracting voltage across one component from the total voltage
• Calculating voltage across a single component in a series circuit

  Multiplying current by resistance of the specific component (Ohm's Law)
• Components with greater resistance in a series circuit


  Will have a higher share of the voltage
• In a series circuit, if any component is disconnected or broken, the whole circuit will stop working
• Total voltage in a series circuit is equal to the sum of voltages across individual components
• Measuring voltage across a component in a series circuit


  Using a voltmeter connected in parallel across the component
• Measuring current in a series circuit

  Using an ammeter placed in series within the main loop
• Very few things are actually connected in series in practice
• Parallel circuit


  • Contain more than one loop
• Calculating current in a series circuit

  Dividing total potential difference by total resistance (Ohm's Law)
• Potential difference in series circuit

  Shared across all components
• Calculating total resistance in a series circuit


  Summing individual resistances of each component
• Current is the same everywhere in a series circuit
• A common point of confusion in exams is the differences between series and parallel circuits
• Small difference in series and parallel circuits completely changes how we measure current, voltage, and resistance
• Series circuit


  • Only have a single loop and components are connected one after the other