Today's Lesson on Series & Parallel Circuit during Science Lesson on 25 August 2009

Today's lesson, we learnt about Series & Parallel Circuit.













THIS IS AN EXAMPLE OF A SERIES CIRCUIT :

• Series circuit has only ONE PATH for current to flow through


• Current is the same at any point.


• This is the formula for resistance for teo resistors in series:

- R = R1 + R2

One disadvantage is, if one of the light bulb can't work, current will stop flowing.

WHAT HAPPEN IF THE RESISTORS ARE CONNECTED IN...

• Overall resistance increases.


• Current decreases.


• Bulb is dimmer (less bright).

A series circuit has more than one resistor (anything that uses electricity to do work) and gets its name from only having one path for the charges to move along. Charges must move in "series" first going to one resistor then the next. If one of the items in the circuit is broken then no charge will move through the circuit because there is only one path. There is no alternative route. Old style electric holiday lights were often wired in series. If one bulb burned out, the whole string of lights went off.

Next I will talk about PARALLEL CIRCUIT:

• Parallel circuit has MORE THAN ONE PATH for current to flow


• Current from battery = sum of current in separate path (like the picture below)

• Voltages are equal across the branches.
• Parallel circuit has more than one path for current to flow.

The advantages are current become bigger and if a light bulb cannot work, other light bulb would still light up...

The formula for parallel circuit is Current from battery = sum of current in separate paths ( P = Q + R )

Total resistance, R, (1/R1 + 1/R2)-1 or either 1/R = 1/R1 + 1/R2

What happen if resistors are connected in...

• Overall resistance decreases.
• Current increases.
• bulb is much more brighter.

A parallel circuit has more than one resistor (anything that uses electricity to do work) and gets its name from having multiple (parallel) paths to move along . Charges can move through any of several paths. If one of the items in the circuit is broken then no charge will move through that path, but other paths will continue to have charges flow through them. Parallel circuits are found in most household electrical wiring. This is done so that lights don't stop working just because you turned your TV off.