Current and circuits

• Series circuit

  • there is one single loop (one pathway for current to flow)
  • example - old Christmas light
  • when one burns out, they all go out
• Parallel circuit

  • there are loops within a loop (multiple pathways for current flow)
  • example - power bar
  • when one burns out, the others still work
• Current - the amount of charge or electrons that passes a point per second
• Electrons move from negative to positive (not the same as an electric field)
• Current (I) is measured in Amperes (a) using an ammeter connected in a series circuit
• How do we know the multimeter is measuring current?

  is in a series/ the dial points to (a)
• Batteries create voltage, which is the amount of electrical potential energy per unit charge available for doing work
• Voltage is what causes the movement of electrons and creates a current (push)
• Measured in volts (v) with a voltmeter which is connected parallel in the circuit
• How do we know the multimeter is measuring voltage?

  in a parallel circuit, measured on (v)
• A resistor can id any device in a circuit that disrupts electron flow generating heat (thermal energy) or light
• Resistance is measured in ohms (Ω) with an ohmmeter
• Ohm’s Law: V = IR

  • current is directly proportional to voltage - as (i) goes up, (v) goes up
  • current is inversely proportional to resistance - as (r) goes up, (i) goes down
• Determining voltage in a series circuit

  • voltage changes through each load
  • individual voltages can be calculated (V= IR) if total current and resistance of each load is known