Electrical Circuits

1. Electrical Circuits

2. Key Question: How do you measure voltage and current in electric circuits? Measuring Voltage and Current Objectives: • Build simple circuits and draw circuit diagrams. • Measure current and voltage in a battery. • Identify electrical conductors and insulators.

3. What is Electric current? • Electric current exists when you have a flow of electrons • Low current = few electrons flowing • High current = a lot of electrons flowing • The amount of electrons flowing means ENERGY is flowing

4. What is Electric current? • Electric current is similar in some ways to a current of water. • Like electric current, water current can carry energy and do work. • A waterwheel turns when a current of water exerts a force on it.

6. Batteries • A pump is like a battery because it brings water from a position of low energy to high energy.

7. Electric Circuits • An electric circuit is a complete path through which electric current travels. • A good example of a circuit is the one found in an electric toaster.

8. Complete Circuits • Form a completely closed and isolated system. • There no open ends or gaps • This is NOT a complete Circuit, Why?

9. Complete Circuit Current will only flow through a closed circuit

12. Electric Circuits • Wires in electric circuits are similar in some ways to pipes and hoses that carry water.

13. Direct Current (DC) • Have you ever looked at your phone charger, computer charger, or electronic device’s plug and read something like – • “5 Amp AC” or “5 Amp DC”? • AC means Alternating Current • DC means Direct Current

14. Electric Circuits in Direct Current • When drawing a circuit diagram, symbols are used to represent each part of the circuit.

15. Electric Circuits • Electrical symbols are quicker and easier to draw than realistic pictures of the components.

16. Electric current • Electric current is caused by moving electric charge. • Electric current comes from the motion of electrons. • Current is measured in Amperes – (A or Amps) current

18. Resistors • A resistor is an electrical device that uses the energy carried by electric current in a specific way. • Any electrical device that uses energy can be shown with a resistor symbol. • Resistance is measured in Ohms –

20. Current in a circuit • Current only flows when there is a complete and unbroken path, or a closed circuit. • Flipping a switch to the “off” position creates an open circuit by making a break in the wire.

21. Voltage • Voltageis a measure of electric potential energy, just like height is a measure of gravitational potential energy. • Voltage is measured in volts (V). • You need to remember that the phrase “what is the means electric potential difference means what is the voltage?

22. Voltage • A difference in voltage provides the energy that causes current to flow.

23. Voltage • A useful meter is a multimeter, which • can measure voltage or current, and sometimes resistance. • To measure voltage, the meter’s probes are touched to two places in a circuit or across a battery.

24. Current and voltage • Electric current is measured in units called amperes, or amps (A) for short. • One amp is a flow of a certain quantity of electricity in one second. • The amount of electric current entering a circuit always equals the amount exiting the circuit.

25. Natural circuits • These are some examples of natural electrical circuits: • The nerves in your body form an electrical circuit that carries messages from your brain to your muscles and other parts of the body. • The tail of an electric eel makes a circuit when it stuns its prey with a jolt of electricity. • An electric circuit with a large amount of energy is formed when lightning carries electric current between clouds and the ground.