Circuits Electric circuit complete closed path that electrons

Circuits

Electric circuit • complete, closed path that electrons flow through

Circuits need three basic parts: • Energy source – battery, photocell, generator

Circuits need three basic parts: • Load – something that uses the energy by changing it into other forms

Circuits need three basic parts: • Wires – connect energy source to the load

A switch can be used to open and close a circuit

“on” • circuit is closed and electrons can flow

“off” • circuit is open and electrons can’t flow

Common Circuit Symbols

How would you draw this diagram?

Two main types of circuits:

Series circuit • all parts are connected in a single loop

Series circuit • A break in the circuit stops the flow of electricity to all other parts of the circuit

Series circuit • Multiple light bulbs (loads) share the current and make the bulbs dimmer

So Why Use a Series Circuit? • Useful in burglar alarms

Parallel circuit • parts are connected side by side with more than one path to travel through

Parallel circuit • A break in the circuit doesn’t stop the flow to the remaining devices

Parallel circuit • Multiple light bulbs will retain the same brightness

Parallel Circuits • The more paths the LESS the resistance – Water example: added pipes coming from a large tank will allow more water to flow out than a single pipe.

Parallel circuit • Each pathway can be separately switched off w/out affecting the others

Series or Parallel Circuit?

Series or Parallel Circuit?

Series or Parallel Circuit?

Series or Parallel Circuit?

Series or Parallel Circuit?

Christmas Lights

What type of circuit wires your house?

A few Questions About Circuits

Which circuit has the brighter globe? Why do you think this occurs?

Which circuit has the brighter globe(s)? Why do you think they are brighter?

Which circuit has the brighter globes? Why do you think this happens?

If you wanted to light up two globes as brightly as possible using one battery, which is the better way to do it?

Which of the circuits will have the brighter globes?

Which of the circuits will have the brighter globes?

Household Circuit Safety

Broken wires, water, or overload can cause circuit failures … which can do a lot of damage

Fuses • contain a thin piece of metal that melts if current is too high, opening the circuit

Fuses • Has to be replaced to complete the circuit again

Circuit breaker • piece of metal bends when it gets too hot which flips a switch and opens the circuit

Circuit breaker • Has to be reset to complete the circuit again

GFCI – found in individual outlets and acts like a small circuit breaker