Electricity: Conductors, Insulators & Circuits

Electrical Conductors

• Electrical conductors allow energy to pass through them easily.
• Examples of conductors include steel, silver, gold, water and copper.

Electrical Insulators

• Electrical insulators do not allow energy to pass through them easily.
• Examples of insulators include wood, glass, rubber and oil.

Key Variables in Experiments

• Variable: The factor being changed or investigated.
• Variable: The information being collected as data.
• Variables: Factors kept constant to ensure a fair test.

Electrical Components and Their Functions

• Cell: Transfers chemical energy into electrical energy.
• Switch: Allows a circuit to be easily broken and reconnected.
• Battery: Transfers chemical energy to electrical energy.
• Motor: Transfers electrical energy into movement energy.
• Lamp: Transfers electrical energy into light energy.
• Ammeter: Measures the number of amperes of current.

Circuit Types

• Series Circuit: Everything is connected in one loop across the terminals of the battery.
• Parallel Circuit: There is more than one pathway around the circuit. The circuit can split or join.

Brightness in Series Circuits

• Adding more lamps to a series circuit increases the resistance.
• Increased resistance reduces the current flowing through the circuit.
• Reduced current means the lamps will not shine as brightly.

Rules for Good Circuit Drawings

• Use a ruler and pencil.
• Draw wires as straight lines.
• Use circuit symbols for components.
• Do not leave gaps between wires and components.

Electrical Conductors vs. Insulators

• An electrical conductor allows electricity to pass through it easily.
• An insulator does not allow electricity to pass through it easily.
• Insulators essentially block the flow of electricity.

Heat Conduction

• A conductor allows heat energy to move through it easily.
• In conduction, particles near the heat source vibrate faster.
• These vibrations are passed to the atoms next to them.
• The amount of vibrations indicates the temperature.

Thermal Conductors and Insulators

• Examples of good thermal conductors: electric iron, pot handles, saucepan.
• Examples of good thermal insulators: hair straighteners, window blinds, clothes, blankets.
• Particles are closely tightly packed in good conductors.

Light Sources

• Light sources: the sun, a candle, a fire and a flashlight.

Law of Reflection

• The light ray hits the surface at an angle.
• It is reflected at the same angle.
• The angle of incidence and the angle of reflection are always the same.

Luminous vs. Non-Luminous Objects

• Luminous objects produce their own light.
• Light travels in a straight line directly from the source to your eye.
• Non-luminous objects do not produce their own light.
• They can be seen because they reflect light from luminous objects. Light travels in a straight line directly from the object to your eye.

Types of Reflection

• Specular reflection occurs with smooth surfaces; light rays reflect at the same angle.
• Diffuse reflection occurs with rough surfaces; light rays scatter in different directions.

Shadows

• A shadow occurs when an object blocks light.
• It creates a dark area behind the object.
• The dark area is called a shadow.

Changing Shadows

• Shadows can change by:
  • Moving the object.
  • Moving the light source.
  • Changing the size/shape of the object.
  • Using different light sources.