CIRCUITS



CIRCUITS

Electrical circuits have to be a complete loop or path.

A SWITCH can open (break) a circuit or close (complete) a circuit.

Energy is transferred from the battery to the bulbs / motors / heater in a circuit.

CIRCUIT SYMBOLS

|Component Name |Circuit Diagram |

|Battery | |

|Switch | |

|Bulb | |

|Connecting Wire | |

|Motor | |

|Ammeter | |

|Voltmeter | |

CELLS & BATTERIES

A cell is a single energy electrical energy source (we usually call this a battery)

A battery is a collection of cells connected together.

The energy change in a cell or battery is Chemical Energy to Electrical Energy.

ELECTRONS

Static Electricity is caused by excess charges on a material.

Electrons are part of atoms that have a negative "electric charge".

ELECTRICAL CURRENT

In a circuit, CURRENT is a flow of electrons in the wires.

MEASURING CURRENT

Current is measured using an AMMETER.

The units of electrical current are Amps or Amperes (A).

The ammeter is connected in series.

VOLTAGE

Voltage is a measure of the energy carried by the charges in a circuit.

MEASURING VOLTAGE

Voltage is measured using a VOLTMETER.

The units of voltage are Volts (V).

The voltmeter is connected in parallel with a component.

SERIES Circuits

In a series circuit all of the components are connected in ONE loop.

The current is the SAME all the way round a series circuit.

The voltage is SHARED in a series circuit.

PARALLEL Circuits

In a parallel circuit components have their own separate loops.

The current SPLITS between the separate loops in a parallel circuit.

The voltage is the SAME across each branch in parallel.

ELECTRONIC Systems

All electronic systems have 3 stages

INPUT ( PROCESS ( OUTPUT

Input stages include microphones, switches light sensors and temperature sensors.

Output stages include motors, buzzers, loudspeakers and heaters.

Logic gates are a type of process stage.

A truth table shows us what a logic gate does.

|AND gate | |OR GATE | |NOT gate |

|[pic] | |[pic] | |[pic] |

Input A |Input B |Output | |Input A |Input B |Output | |Input |Output | |OFF |OFF |OFF | |OFF |OFF |OFF | |OFF |ON | |OFF |ON |OFF | |OFF |ON |ON | |ON |OFF | |ON |OFF |OFF | |ON |OFF |ON | | | | |ON |ON |ON | |ON |ON |ON | | | | |

Questions – complete in your class notebook page.

1. Draw the circuit symbols for the following electrical components:

a. A bulb

b. A motor

c. A battery

d. A connecting wire

2. What does a battery supply in a circuit?

3. What is the energy change that takes place in a battery?

4. What do we call the 2 types of electrical charge?

5. What is an electrical current?

6. Name the device used to measure the current in a circuit.

7. Name the units that current is measured in.

8. Draw a simple circuit with a battery, motor, switch and the correct meter to measure the current.

9. Which statement correctly describes current in a series circuit:

A. The current in a series circuit decreases as it moves away from the battery

B. The current increases as it moves away from the battery

C. The current stays the same all around the circuit

10. What is the definition of voltage?

11. Name the device used for measuring voltage.

12. Name the units that voltage is measured in.

13. Which statement correctly describes voltage in a parallel circuit:

A. The voltage in a parallel circuit splits between the branches

B. The voltage in a parallel circuit increases as it moves away from the battery

C. The voltage in a parallel circuit is the same across each branch

14. Draw a circuit diagram with a battery and 2 bulbs connected in parallel.

15. State one advantage of connecting devices in parallel.

16. What are the 3 stages of any electronic system?

17. Name 3 input devices

18. Name 3 output devices

19. Draw the correct symbol for an AND gate

20. Draw the truth table for an OR gate

21. Describe in words what a NOT gate does.

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