Series and parallel circuits

In electrical circuits series and parallel are two basic ways of wiring components. As a demonstration. Consider a very simple circuit consisting of two light bulbs and one 9V batteryIf a wire joins the battery to one bulb then the next bulb then back to the battery in one continuous loop, the bulbs are said to be in series. If on the other hand each bulb is wired seperately to the battery in two loops the bulbs are said to be in parallel.

Series Circuits

The current has to pass through all the components in the loop. an ammeter placed anywhere in the circuit would read the same amount.

• To find the total resistance of all the components add together the individual resistances.

R_total = R₁ + R₂

for two components in series each having resistance R₁ and R₂ respectively. For more than two components add in their respective resistances.

• To find the current, I, use Ohm's law.

I = V/R_total

• To find the voltage across any particular component with resistance R_i , use Ohm's law again.

V=IR_i

Where I is the current as caculated above.

Note that the componants divide the voltage acording to their resistances so V₁/V₂ = R₁/R₂