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Electricity

Electricity. 4th grade Science. What is an electric current?. A flow of electrical charges. Important Fact Electric current will only flow through a complete circuit. Making a Circuit. You need a path to carry the electricity. This path along which an electric current flows is a circuit.

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Electricity

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  1. Electricity 4th grade Science

  2. What is an electric current? A flow of electrical charges

  3. Important FactElectric current will only flow through a complete circuit.

  4. Making a Circuit • You need a path to carry the electricity. This path along which an electric current flows is a circuit. • 3 basic parts of a circuit • power source (ex. battery) • load (a lamp or a bulb, etc.) • connectors (ex. wires) They carry the electric charges between the power source and the load.

  5. Making a Circuit • Many circuits have a switch. • It turns the electric current on and off. • Ex. the lights in a room turn on with a switch • Closed Vs. Open Circuits • The circuit cannot have any breaks or the electric current can not flow. • A closed circuit is complete and unbroken. • An open circuit has breaks or openings.

  6. Did you Know? When a bulb burns out, a wire inside of it breaks in two. This causes the circuit to no longer have a complete path. It is now an open circuit and electric current cannot flow through it.

  7. Let’s try it! Materials: power source (battery), connectors (three wires), load (bulb), and switch Investigation: Create a closed circuit that will allow the electric current to flow.

  8. Can you turn this complete, closed circuit into an open circuit? Open the switch!

  9. What is a series circuit? • All electrical charges flow in the same direction • The parts are connected in one loop • Electric current moves along one path • current goes from power source to load then to another load and finally returns to power source [through wires] • All of the parts are connected one after another

  10. Let’s try it!Build a series circuit... Materials: power source (battery), battery holder, connectors (three wires), 2 loads (bulb), and bulb holders Investigation: Create a series circuit.

  11. Series Circuits

  12. Let’s try it!Build a series circuit... Unscrew one of the light bulbs. Does the light bulb still light up? Why or why not?

  13. Questions to Ponder... • One bulb burns out in a series circuit. Will current flow in the circuit? • A string of small lights are an example of a series circuit. If the first light goes out, what happens to the others? What if the last light burns out?

  14. What is a parallel circuit? • All electrical charges flow through more than one path. These different paths are referred to as branches. • Some of the electric current flows through one branch and some flows through another branch

  15. Let’s try it!Build a parallel circuit... Materials: power source (battery), battery holder, connectors (4 wires), 2 loads (bulb), and 2 bulb holders Investigation: Create a parallel circuit.

  16. Parallel Circuits

  17. Let’s try it!Build a parallel circuit... Unscrew one of the light bulbs. Does the light bulb still light up? Why or why not?

  18. With a parallel circuit... • If any branch of the parallel circuit breaks or is removed, current will still flow through the other branches. • If the light bulb on one branch burns out, the light bulbs on other branches will still glow.

  19. Did you know? You can have a combination of a series and parallel circuit. Many circuits in electrical devices, even circuits in your home, are combination circuits!

  20. What affects electric current? • Voltage • strength of a power source • a power source with more voltage can produce more electric current • measure in units called volts

  21. What affects electric current? • Resistance • ability of a substance to oppose or slow down electric current • increasing the resistance of a circuit decreases the flow of electric charges • also allows electrical energy to be changed into other forms of energy [Ex. light or heat] • Very little resistance…copper wires-can carry a great deal of electric current *CONDUCTOR • Large amount of resistance…rubber-it is difficult to make electric current flow through it *INSULATOR

  22. Questions to Ponder... • If you add bulbs to a series circuit, the circuit has higher resistance. What happens to the electric current in the circuit? • If you decrease the resistance of a circuit, what will happen to current in the circuit?

  23. What is a short circuit? A path with almost no resistance It can stop the rest of the circuit from operating properly. Can be dangerous! The wire heats up and may cause a fire.

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