Light and Sound: Properties and Behaviors

Light and Sound Comparison

• Light is a form of energy.
• Light is produced as electromagnetic radiation waves.
• Sound requires particles (solid, liquid, or gas) to travel.
• Light does not require particles to travel.
• Light travels very fast at a speed of 3,000,000 m/s.
• Sound travels slower at a speed of 330 m/s.
• Light, sound, and both light and sound can be converted into other forms of energy.
• Light, sound, and both light and sound can be reflected by other objects.
• Sound travels in all directions.
• Light travels in straight lines but can be refracted and dispersed.
• Both light and sound can travel in waves.
• Light and sound travel in rays.

Vocabulary

• Conductor: A material that allows electrons to move easily.
• Insulator: A material that restricts the flow of electrons.
• Circuit: A path for electrical current to flow.
• Current: The flow of electric charge.
• Voltage: The electric potential difference that drives current.
• Ammeter: A device used to measure electric current.
• Amperes: The unit of measurement for electric current (A).
• Volts: The unit of measurement for voltage (V).
• Resistance: Opposition to the flow of electric current, measured in ohms (Ω).
• Series: A circuit in which components are connected one after another, so the same current flows through each.
• Parallel: A circuit in which components are connected side by side, so the voltage is the same across each.

Electrical Conductors and Insulators

• Electrical conductors allow charged particles to move through them.
• Electrical insulators do not allow the current of charged particles to pass through them.
• Copper is a good electrical conductor.
• Plastic is an electrical insulator.
• Air is a good resistor due to the difficulty for charged particles to move freely through it.
• Semiconductors, like germanium and silicon, are insulators in pure form but become conductors when combined with another substance.
• Silicon is used to make conductors used in computing.

Measuring Electric Current

• Electric current is the flow of charge.
• Electric current is measured by counting the number of electrons passing a point in a circuit in one second.
• The unit of measurement for current is amperes (A).
• A milliampere (mA) is a smaller unit of current, where 1000mA = 1A.
• An ammeter is used to measure current in an electric circuit.
• A multimeter can measure current and many other aspects of a circuit.

Current, Voltage and Resistance

• Current is the flow of electrons within an electrical circuit or system.
• Electrons must flow in the same direction to use electrical energy in a circuit.
• Materials like copper are used as the core of cables because electrons move easily.
• Current is like the rate of water being forced through a hose.
• A cable's thickness determines how much current it can carry.
• Components and wires can only safely handle a certain level of voltage and current, or they will break/fail.
• Voltage is the pressure that pushes electricity around a circuit.
• Voltage's unit of measurement is the volt (V).
• The higher the voltage, the more electricity that can flow, the lower the voltage, the less electricity that can flow.
• Voltage can be referred to as potential difference.
• Resistance is like an obstruction in a hose.
• The more resistance, the less the flow of current.
• Conductors allow electrons to move easily due to their low internal resistance.
• Copper, silver, aluminum, and gold are examples of conductors.
• Insulators restrict the flow of electrons due to their high resistance.
• Paper, glass, wood, rubber, and plastic are examples of insulators.
• Higher resistance means lower current, and lower resistance means higher current.
• Resistance is measured in ohms (Ω or R).

Ohm's Law

• In an ohmic conductor, resistance does not change with voltage.
• Voltage and current are directly proportional, or V = R x I
• V is voltage (in volts), I is current (in amperes), and R is resistance (in ohms).
• When voltage is increased, a lamp in a circuit will glow brighter because there's greater current.
• As voltage increases, so does the current.
• A plot of voltage (V) on the y-axis against current (I) on the x-axis of an ohmic conductor produces a straight line.
• Voltage and current are directly proportional.
• If voltage is doubled, the current is doubled.