Sound Optics and Heat

What is sound?

The movement of a wave of pressure through air or another medium.

What unit measures sound?

The decibel (dB).

What determines how fast sound travels?

The medium it moves through — some allow faster travel than others.

Does sound travel faster or slower than light?

Much more slowly.

How does the ear detect sound?

Hair cells respond to small pressure differences from sound waves and pass the signal along nerves to the brain.

What is optics?

The study of light, its behavior and its properties.

What is visible light?

The part of the electromagnetic spectrum we can see.

Name two other parts of the electromagnetic spectrum.

X-rays and radio waves.

What is the range of visible light?

From 740 nanometers down to 380 nanometers.

How do wavelength, frequency and energy relate?

Smaller wavelength means higher frequency and higher energy; longer wavelength means lower frequency and lower energy.

What is absorption, in optics?

The change of light energy into heat energy at the surface of an object.

What is scattering?

The process by which light is reflected in multiple directions.

What is reflection?

A light ray striking a surface and bouncing off it, creating an angle between the rays.

What is refraction?

The bending of a light wave as it passes into a medium such as water, making objects appear bent.

What does refraction literally mean?

Bending.

What is heat?

The transfer of energy from objects of higher temperature to objects of lower temperature.

What units measure heat?

Joules — calories are another measure of an object's internal energy.

What is the 0th law of thermodynamics?

Two systems in thermal equilibrium with a third system must all be in equilibrium.

What is the 1st law of thermodynamics?

The thermal energy of an isolated system is constant.

What is the 2nd law of thermodynamics?

An isolated system naturally moves toward disorder as time progresses.

What is the 3rd law of thermodynamics?

As a system's temperature decreases, its disorder moves toward a constant.

What are the three methods of heat transfer?

Conduction, convection and radiation.

What is conduction?

Heat transfer through direct contact between two objects.

What is convection?

Heat transfer in liquids or gases, where warmer particles rise and colder ones sink.

What is radiation, as heat transfer?

Heat transferred by electromagnetic waves — it needs no matter at all.

Which heat transfer method works in a vacuum?

Radiation.

Give an example of radiation as heat transfer.

Feeling warmth from a fire without touching it.